Datsun was very clever using the same 6-cylinder engine/transmission and drivetrain platform from 1970 to 1983.
Not only did this make them easy to manufacture, but it lets an enthusiast mix parts from different years to create the perfect Z.
The secret is that the heavier 280ZX used physically identical L28 engines and transmissions from '79 all the way through 1983, making them simple bolt-ins into earlier Z models. And since a great many 280Z's and ZX's are in junkyards, what better time to breathe some life back into your car?
So here is my formula for a very quick and fun 1970-78 Z, along with tested performance tips. 240-260 folks would want to swap everything, while 280Z and ZX people would should keep their injection and ignition and change the drivetrain parts only. Covered below is a LOT of information, so I broke everything into 11 sections for readability.

FIRST - the car

Unlike Chevy Chevelles of which many millions were made, there are only a few thousand 1970-83 Zs left. Rust, wrecks, and rebuilds have sidelined most of them over the decades. And despite the nostalgia, I don't see a problem removing the old engine and drivetrain and replacing them with other versions. Without your intervention the car would likely never see the street again. So there's nothing wrong with restoring it the way you want, it's your car.

If you want to find a base model to use for your fantasy racer, try to find one of the first 12,000 or so 240Zs made from 1970 to early 1971. These are identified by a "solid" B-pillar with a "240Z" badge behind the side window, and two grills on the rear hatch. These '70-71s were the lightest of all ZCARs, at about 2200 lbs, making them the best for performance buildups. Later models went to the Z badge and removed the hatch grills. Unfortunately the weight went up a few hundred pounds too.

I'm not going to pretend that these old Zs are easy to find however, you'll be lucky to even see one on the street. Strangely though, while 240Zs are hard to find in many cities, having been stolen or wrecked, many can still be found in rural areas. I've seen old 240Z in fields and driveways while in the country here in Virginia. So keep an eye open.

SECOND - the engine

Datsun made several blocks over the years, varying in bore and casting methods. Compared to the 240Z, the 260Z had a longer stroke, while the 280Z/ZX had both a longer stroke and  a larger bore.
The way to identify the block is to look on the driver side of the engine, to the right of the motor mount. That's where they cast the block number.

Except for the turbo guys, it seems that only in the last few years have people been focusing on the F54 engines. I think the reason is that when Zcars were popular for racing in the late '70s and early '80s, the ZX motors were not available in junkyards.
And people probably thought: "...why would I want a slow ZX motor".  What they didn't realize is that minus power steering, AC, and other ZX plumbing, the F54 is the most powerful and refined of the L-series engines. It was Nissan's final evolution of the Z engine, with more horsepower and torque than earlier motors. It had to be to carry the heavy ZX. The early Z engines were designed on paper in 1969, the final ones on computer in 1980.
Personally, I like the idea of putting a late model F54 in a 240Z, and converting it back to carbs. Very retro, but totally functional and quick.

So if you want to install the best motor in your Z, go for the last of the L28's, the 1981-1983 F54. It's cylinders are "siamesed" meaning that instead of coolant flowing between all the cylinders as on earlier models, they are connected between 1-2, 3-4, 5-6 with cast webbing. This was done for more rigidity. In addition, all Datsun did to make the F54 a turbo motor was to replace the flattop pistons with dished ones ( to lower compression), and add a turbo head with better exhaust ports. So there really isn't a "turbo block", the substitution of pistons and head are what created the different motor.

It can be tricky determining exactly what's in a car you find, as many have had head and block swapped over the years. One way is to look for the head code between the 1st and 2nd spark plugs. Check out the head page to see which head came with which block. Sometimes you have to do a little detective work to figure out what you have.

COMMENTS:

• PISTONS The F54 motors with P79 heads ('81-83) have flat-top pistons. All other L28 motors(N42,N47,P90, P90a) came with dished pistons.
  In a performance engine, flattop pistons create a higher-quench mixture and allow for higher performance combustion chambers. Dished pistons are usually used to lower emissions.
  
  
• HEADS The P79, P90 and P90a heads are the three heads found on ZX F54 blocks, and have the same chamber volume and dimensions (53.5cc).  The P79 has round exhaust ports with steel liners that heat red-hot to reduce emissions, some say they reduce flow, but I've pulled a 13.9 1/4 mile with my P79, so it can't flow too badly.
  My guru racer buddy says Nissan finally "got it right" on the P90, and he feels it's the best flowing head out there. I have to agree, I just modified one this year, and it's design incorporates the best features of all the heads: square exhaust ports, high-quench chambers, and steel seats. Check out my P90 and P79 pages for more modification details.
   
• HORSEPOWER A lot of factors affect horsepower, and it's best not to fixate on numbers. But as a baseline the '75-80 motors put out about 135 net, the '81-83 motors 145 net. BTW, the little plate in the 280Z's engine compartment says 170hp SAE which is 135 net.
  

THIRD - carburetion

I've been told the most common mistake on any high-performance motor is to over-carburate. You see guys putting Holly Dominator 1150 carbs on a stock 5.0 V8, and wonder why it runs badly. The optimum air/fuel ratio for all car engines is something like 14:1. Either the mixture and intake flow is correct for the engine demands, or it isn't.

Luckily the stock 1970-1973 SU is a great carb for both street and performance, and automatically meters the gas depending on the airflow through it. So whether you are stock or have a cam with giant valves, with the proper needle the SU carb tries to keep the correct mixture from idle to redline. A simple, accurate design.

The "good" SU's were from 1969-1972 and will have 4 or 3 screws holding down the domed piston depending on which year it was made. The year makes no difference for performance, as the nozzles and needles from different years interchange. If you have carbs with the square choke flap in the inlet or flat tops then you have horrible emission carbs. Exchange them.
A buddy of mine has a Mikuni 6-pak which runs great flat out, but he has had to spent a lot of time tuning them, very finicky. So for street performance and autocrossing I would stick with SUs.

CARB INTAKE MANIFOLDS

A 240/260 carb intake will bolt right up to any L28 head. The bolts are 8mmx1.25.

• The 1970-73 used the E88. I've heard of another (E46?) but never seen it.

• The 1974 260Z used the N36. This intake manifold is rumoured to produce 10hp more than the 240 one. If it's true, simply bolting it on a stock motor probably wouldn't do much. A modified motor that needs more flow would benefit more: if it's true.

The manifolds are actually 2-piece: left and right, with a water line connecting them. Supposedly the water line is dual purpose, keeping the manifolds cooler (since they sit over the exhaust) and also warming the intake more quickly during startup. However, I don't see any performance reason for removing the water lines, as they keep the intake temperature stable.

• the '70-71 240 used "N27" needles and related nozzles.
• the '72 manual trans car used N54 needles, the '72 automatic used N58, both with the same '72 nozzles.
• the '73 nozzles/needles were emissions designs, not recommended for performance.
• SM needles from British SU's are excellent for performance. I'm not sure who carries them now though.

My favorite setup is 1970-'71 nozzles, SM needles on a set of 1970-'72 carbs, 260Z "N36" intake.

CONVERSION NOTES
240 needles were designed for a 2.4 liter motor with small valves. 240Z needles on a L28 will work fine on the street, but remember a L28 is 17% larger. With larger valves and displacement, it fuel needs are a lot more than the little L24, especially if a hot cam and header are used. In other words, using stock 240 needles/nozzles on a L28 is like taking a carb calibrated for a 305 V8 and putting it on a 350! High-Performance? I don't think so.
I used the N27 needles originally on my L28, but the engine would stumble past redline. I later found the SM needles pulled way harder and made a big difference in acceleration and now swear by them.

• Buy new rubber bushings from the dealer to hold the SU float bowls to the carbs, make sure they're snug and level. Keep the stock fuel return rail and use an aftermarket electric fuel pump with 3-5 psi. Higher pressure can overpower the needle valves, lower causes the bowls to run dry on heavy acceleration. Don't use an injection fuel pump (30+psi, too high.)
• Use any electric fuel pump that can provide 3-5 psi. Always mount an electric pump as close to the gas tank as you can. It's better to "push" the gas rather than "pull".
• Look in Motorsport Auto or Victoria British catalogs for recommended pumps. The Purolator brand electric pumps are reliable I'm told, but are very noisy.
• Remove the little copper mesh filters in the SU float bowl inlets. These can restrict flow. I have a Purolator "clear" fuel filter installed where the hose comes off the firewall. This is easy to inspect and clean.
• Retain the water cooling through the intake manifold.
• Don't block off the PCV hoses. It's important that the crankcase be vented to the intake so the motor stays clean. Using a little K&N breather on the valve cover looks cool, but stinks the car up with fumes.
• Don't disable or block off air or emissions hoses. It dirties the motor and won't increase power.
• Also keep the "flow-valve" on the driver fender well connected. This pulls fumes from the gas tank and burns them in the carbs.

FOURTH - the transmission

Borg T5 and lightened turbo flywheel

Datsun seems to have made four different 5-speeds for Zcars

• One from '77-78
• One from '81 to 83.
• A Borg-Warner T5 in 1983

Nissan called the '77-78 trans a "wide ratio", while the '81-83 is called a "close ratio" 5-speed. The early one has the lowest 1st and 2nd gears for acceleration. The later has a taller 1st/2nd, but also has a much taller 5th for cruising. Your choice.
According to a Z Doc friend who rebuild transmissions, the early 5-speed is a 4-speed with 5th and reverse sharing the same fork. He said it's common for people to "blow" 5th gear as the fork is weaker. The later 5-speed is a genuine 5-speed and is stouter.

I call the early one a 280a and the later a 280b to keep them straight. The British Haynes manual shows an odd 5-speed in 1979 only. It had a 5th gear ratio midway between the 280a and 280b, can be identified by a largish rectangular plate bolted on the top of the trans under the shifter.
I kind of ignore that year anyway as Nissan was still trying to figure out the ZX drivetrain platform. So I suspect this was a British only model, and have only seen the early and late 5-speeds in junkyards.

BORG WARNER T5

My page on installing a Borg-Warner T5 in a 1st generation Z.

Keeping the speedometer correct

Everyone gets confused about how to calibrate the speedometer after swapping differentials, it's actually very easy. The speedometer is metered by a plastic, toothed cog on the end of the speedometer cable that screws into the transmission. This cog is paired with the differential, not the trans. So it doesn't matter which trans you have, all you do is select the proper cog for the rear-end ratio you have in the car. While they are colored for easy identification, the Nissan dealer only has them in their part list as "17, 18, 19, 20, or 21" tooth cogs. Here's how to figure out which is which.  

But don't buy the whole cog-body assembly, just buy the toothed cog, about $14 at the dealer. A cheaper way is to simply go to the  junkyard and pull the cogs from several wrecked cars until you find the color you need.

NOTE: Hard to describe online, but there are 2 different cog "bodies" that hold the cogs, a A '75-80, and '81-83. These bodies have different cog "offsets". If you look closely in the picture above, notice how the red cog is offset to the right, and the blue to the left? This means you must keep the body with the trans it came in, and only swap the cog. Otherwise the cog won't mesh the proper way inside the trans.
In other words, if you have a '75-79 trans, you must use the '75-79 sleeve and swap on the white (or other) cog of your choice.  If you have a 1981-83 trans, use the later cog body. It's easy, just drive a small pin out to change the cog.
The weird one is the larger red 4.11 cog, which requires a later ZX sleeve to fit into the older '77-'79 trans. Will it fit into A 280b? I don't know.

• On early 240's, you will have to cutout about 2 inches of metal from the front/right edge where the shifter goes through the trans tunnel. Otherwise the throw into 5th gear will hit. This cutting is the price of a 5-speed trans, and is not a big deal at all, the console covers it.

FIFTH - the flywheel and clutch

This is a 2+2 flywheel and clutch.

Measure the width of your flywheel's shiny clutch contact surface.

• If it's 225mm wide then you have a coupe version which uses a 550lb pressure-plate.
• If it's 240mm wide then you have a 2+2/turbo version with a 780lb plate and a wider disc.

Both flywheels are the same at weight at 23 lbs, and the diameter is the same (only the contact area is wider). But a turbo pressure plate and disc clutch are definitely heavier than coupe version by a few pounds. So how much performance is actually lost with a heavier assembly? A good one to argue at Z meetings...

I haven't tried any of the competition clutches, but truthfully the only time you really need a stronger one is if your engine torque is causing the clutch to slip.
I agree it sounds neat to say your car has a "competition clutch", but it doesn't make the car any faster. I autocross and dragrace my Z, and my stock clutch works fine (really) after 2 years (Zoom brand). A buddy has a Centerforce 2 which feel very solid, but rumor has it the Centerforce One is a stock clutch with only extra weights hanging on the pressure plate fingers.

• LIGHTER FLYWHEEL
  Used for decades to reduce drag on the engine and to make it spin up faster. It won't make the engine develop any more horsepower internally, but can cut down on parasitic drag. Better for track racing than dragracing, as on smaller engines the rotational inertia that helps the car off the line is reduced. This loss of inertia can make the engine rev down quickly between shifts. Some people consider them undriveable on the street, because the engine can stall easily, especially when cold.
  On motorcycles, having a too-light flywheel can make it stall between shifts(!) So keep this trade-off in mind if you want one for your car.
  
  CONVERSION NOTES
  
•  There are 2 versions of flywheels on all '75-83 motors, coupe and 2+2/turbo. 23 lbs each.
  
• Coupe and 2+2 clutches aren't interchangeable because the pressureplate dowel holes won't match the flywheel dowels.
• You can use a Z 5-speed on any year Z block, and any year L28 clutch can be used, but the throwout bearing "collar" must match the style of the flywheel (coupe or 2+2). In other words, if you have a 2+2 flywheel, you need to change the throwout collar to a 2+2 version when using a coupe trans. And vice-versa.
• Auto trans engines have a 1/4" metal spacer between the driveplate and crankshaft, remove this when adding a flywheel.
• A pilot bushing needs to be installed in the crankshaft if using an auto trans engine (they didn't get one).
• Unless you need the accessories, don't use a big 3-row harmonic balancer in front, get rid of it. Compared to a 280Z 2-row it weighs about 5lbs more. I've read that taking 10lbs off a 10" rear flywheel is the equivalent of taking 207lb off the front of the car. So I believe removing 5lbs from the front of the crankshaft is desirable. Also, I've been told the 3-rows like to break up over 6,000rpm. Nissan makes a
  1-row balancer for a reason.
• All balancers have identical TDC timing marks and are interchangeable.

SIXTH - the differentials

4.11 from 200SX turbo

There are several R-200's variations out there, none were limited slip until 1987. Don't try to analyze the confusing table in the Haynes manual, this is the easy way to do it: If the car has a has a R200 then...

Some people have said R180's from regular 200SX's had a 4.11, but I've never checked. It seems odd that Nissan would make a 4.11 for the both the economy and performance models, but apparently so.  The people who told me they have the 4.11 R180 mention problems with the halfshafts though, as the 240Z R180 ones apparently don't fit.

LIMITED SLIP DIFFERENTIALS: Despite the performance of the Z, Nissan only made a limited slip diff very late in the Z's life. They made 2 types a standard clutch LSD, and one with a viscous internal drive. According to an excellent posting on ZCAR.com, the 1987-89 Turbo ZX's had the good 3.70 LSD, and can be identified by it's finned rear cover. This cover needs to be replaced with the smooth R200 cover to fit properly to the 280Z stock curved rear Transverse Link brace. To use the finned rear LSD cover a custom aluminum rear brace needs to be used. Here's the link to the Custom Brace The front driveshaft flange on the 300 ZX limited slip differential needs to be replaced with the one your driveshaft uses. The '88 white SE 300ZX came with the oddball "viscous-drive" R200, and can be identified by a sticker on the driver-side of the diff that says "VISCOUS LSD". This fits a Z, but R200 halfshafts don't lock into them without some serious fabrication of new halfshaft fittings.

NOTE: some 240SXs came with a finned rear cover. Don't be fooled into thinking this is limited-slip, it's not.

If you want performance, get the R200 out of any junkyard '81-83 NON-turbo ZX (3.90), and use a '77-78 5-speed.
If you're speed freak (like me) use the 4.11. These are pretty rare, and are not LSD differentials, but can make your Z a real rocket off the line.  I lucked across one in a '85 200SX turbo in the junkyard. An identical R200, it dropped in perfectly.  It had CV halfshafts which should be left in the junkyard, use standard R200 halfshafts.

BTW: to get halfshafts out, DON"T pry them out or spend an hour unbolting the flange. Simply unbolt the wheel end, and "yank" the halfshaft a hard a few times. A little circlip in the diff holds it but it will pop right out, the yanks don't hurt it. To get them back in, you have to rotate it around as the shaft clicks into the differential in only one position. You can lock it in place by hitting the tire end with a mallet.

TO DETERMINE THE RATIO (internally): If you're not sure which ratio R200 you have lying around the garage, check it this way:
Remove the rear plate (drain the oil of course). Then rotate the large ring gear until you see some numbers stamped into the edge facing you.

• If it's a 3.54 it will read  "39:11"
• If it's a 3.70 it will read  "37:10"
• If it's a 3.90 it will read  "39:10"
• If it's a 4.11 it will read  "37:9"

Someone suggested swapping ring and pinions around to create the ratio of your choice. I checked with my buddy the Z Doc, and he said it's very difficult to get the preload and tooth geometry setup properly (he tried it). Oh well.

R-200 REAR END SWAP

Swapping a R200 rear end from a 280ZX into a 240/260/280 is very popular now due to it's relative ease, and the impressive increase in performance. Even if you have a '75-78 280Z with a R200, you can upgrade it to a 3.90 from a ZX and add some serious acceleration.
All you're doing is replacing rear end and differential parts with 280Z /ZX versions, that's all. NOTE: the R200 and the halfshafts from a 280ZX are the only parts that cross into a 240/260/280Z. The ZX driveshaft and mounting hardware won't.
For 240Zs, just find the entire rear drivetrain out of a 280Z and swap it in, then choose your R200.

For a 240Z/260 R-200 transplant, use these parts from a '76-78 280Z:

• the curved rear crossmember which bolts immediately behind the bottom/rear of the differential. The R-200 sits back by about 1 1/2 inches and needs the curve. Bolts in perfectly. This is a necessary part.

• Get the "mustache bar" that bolts onto the rear differential cover from a '75-78. This is a necessary part. Despite your budget, replace the bar's bushings with urethane ones. I tried to be retro, and replaced mine with new soft stock ones, which allowed the extra torque from the 3.90 to thunk the bar-ends against the floor. This made me realize that thunks are only partially caused by the front mount.

• Get the R-200 halfshafts from a 1976-83 Z-ZXmodel, all are identical. I consider these a necessary part.
  But be careful not to swap the halfshafts as the flange that slips into the differential on the passenger side is 1/4 inch longer than the driver side. So, try to get the "older style" ones from a ZX. Just "yank" them out of the differential. R180 shafts will just fit as they have to be compressed, but why bother with a "maybe" fit, get the R200's. For some reason ZX shafts sealed the grease fittings with plugs.  Remove the plugs and add new fittings, and remember to grease them every 3,000 miles.
  Later ZX's came with CV joint shafts which will fit , but with difficult modifications to the wheel hub which I've never tried. To get halfshafts out, DON"T pry them out, that tears up the seals. Simply unbolt the wheel end, and "yank" the halfshaft a couple of times. A little circlip in the diff hold it but it will pop right out, the yanks don't hurt it.

the longer passenger-side flange is on the right

• Get a good driveshaft from a '76-78 280Z. They are about 20 cm longer than the 240 shaft, which is what you need if using an R200. Strangely, 1975 driveshafts used odd rear bolt patterns and were 10mm shorter and fatter, stay away from those and 1975 R200s.
  You can use a old 240/260 driveshaft, but the do it right and simply swap everything over to R200 parts from a 280Z. 

• The front differential crossmember from a 280Z that bolts to the frame (holds the front  rubber insulator) is thicker and beefier and should be replaced also. Of course you should then replace the actual rubber front differential mount with a '75-78 version.

• The '70' and early '71s differential strap sits forward by about 2 inches compared to later 240 models (different brackets). So if you try a R200 swap on an early cars, the R-200's front mount nuts on the top will hit the strap. I found I had to reverse the bolts, place the nuts on the bottom, and saw off the protruding bolt threads so the mount would flex. I then raised the differential with my floor jack, and placed it very tightly against the strap. Only then was I able to bolt the front crossmember in. Since later 240/260/280's had different strap brackets, they won't have this problem

SEVENTH- the ignition (detailed, lots to read)

Don't waste your time playing with a points distributor. Points distributors were phased out worldwide about 25 years ago for good reason:
the constantly changing dwell and gap required constant tune-ups, and the point-bounce limited top end to about 6,000rpm.
Mods like a solid breaker-plate, or a dual-point Mallory distributor were fine 30 years ago...until electronic ignition was phased in. So the old setup may seem cool and vintage, but do yourself a favor and upgrade to a better ignition.

By replacing the points distributor with a ZX distributor that provides a stable spark out past redline, you will pick up some real power above 5500rpm. Like the line from Motorsport Auto's catalog: "you won't believe you're driving the same car".
If you have a 280Z or ZX stick with what you have, but a 240Z can greatly benefit from upgrading to a factory electronic ignition. You can buy aftermarket systems like Pertronix or Luminition, but Datsun did all the homework already by creating reliable factory distributor.

E12-80 module

The Nissan shop manual says the Nissan module "increases dwell and spark duration at higher revolutions to fire the lean mixtures encountered in newer engines".

So if you have a 240, the trick is to use a 1979-83 280ZX manual-trans distributor, with the module on the side changed to a E12-80. Finding the module separately is tricky, so go to a junkyard and "liberate" a couple of old modules from old Datsuns while you are there. Other Datsuns like the B210 and 510 from 1979-1981 used the E12-80 too.
However, the 1981-83 E12-92 module relies on sensor info from the brain to alter the timing constantly, making it unusable on carbureted motors. It strangely retards the distributor timing about 8 degrees from stock and runs badly. Even advancing the timing makes the engine bog down and slow to accelerate, without the ferocity of the E12-80.
So unless your car came with a E12-92, ALWAYS use the E12-80 module.

HOW TO HOOK UP THE E12-80 MODULE and D2 DISTRIBUTOR INTO A 240Z?
(If you have a 280Z or 280ZX don't do this mod)

• The module must be mounted on a 1979-83 280ZX distributor (won't work on points or D1).
• Connect a key-off +12V supply to the "B" terminal on the distributor IC module and coil +. Then connect the module's "C" terminal to the coil's negative terminal.
• Make sure the metal rear of the module is clean so it can ground itself to the side of the distributor.
• Remove the triangular hold-down plate on the base of the distributor. Burnish it, as well as the spot where it contacts the distributor and replace. This helps everything ground well to the block.
• Use quality spade lugs and wire with TIGHT crimps, and solder the wire/spade connections if possible. Don't solder or crimp onto the module though, just make sure the spades fit on tight.
• A 240 tach will not work with this setup since it's loop wiring can no longer connect to the coil. Replace it with a 75-78 280Z tach and connect the tach sensor lug to the - terminal on the coil. If the tach jumps around, solder a 7500-10,000 ohm resistor inline with the sensor wire to reduce the signal voltage. If it still won't work buy a Autometer #3990 black face tach.
• WARNING: if you have a MSD or Crane, DON'T hookup the module or tach to the coil. The 450 volts will fry it. Follow ignition's hookup guide instead.

DIELECTRIC GREASE

di·e·lec·tric (d-lktrk) noun.
A nonconductor of electricity, especially a substance with electrical conductivity of less than a millionth (10-6) of a siemens.

Unlike the gel used on the defib paddles in an emergency room, dielectric grease is NOT meant to improve conductivity. It's sole purpose is to protect the OUTSIDE surface of metal conductors from corrosion, preventing moisture from getting in, and insulating outer surfaces to prevent arcing. Putting it on distributor cap terminals, rotor tips, or injector contacts is asking for a big headache. Only put it on outer surfaces.
Personally I think the companies deliberately call it "Tune-up grease" to induce sales.

Radio Shack Tuner Cleaner is what you want to use. It 's good to spray onto the contacts and wiper arm in your 280Z airbox, and to clean all connections. Cleans off oxidation and leaves a nice clean surface.
Surprisingly, good old WD40 is recommended too. Audio Magazine (high-end home equipment) recommended using it on the controls of expensive preamps and receivers a few years ago. They maintain it's a high-quality oil with excellent cleaning properties for all conductive surfaces. I agree.

AFTERMARKET IGNITION BRANDS
Both Crane and MSD are battling it out on who has the best ignition. Both use the same concept: provide a multiple spark out to 3,000, and then change to a single hot spark. So the choice is up to you. MSD is popular since hot-rod people religiously copy each other, but I'm mystified over why MSD doesn't provide a rev limiter on ALL their ignitions, instead of just the more expensive ones. The Crane comes with a snazzy built-in adjustable rev limiter and RISC computer chip. I have used both a Crane Hi-6 and a MSD 6A on my carbureted F54, using a E12-80/ZX distributor, both felt similar to me.

PERFORMANCE
I spent some time on the interstate with a stopwatch doing 60-80 and 70-90 runs in the top three gears, comparing a MSD 6A to a just a E12-80 module. The times were within a tick of each other, back and forth. Kind of inconclusive.
The MSD gives smoother idle, needs almost no choke, drives better when cold, and cuts down on my exhaust smell at idle. But despite it's credentials,  I'm not convinced it actually makes the car any faster. Sometimes I feel like the E12-80 alone actually has a little more torque.

I've decided that on a carbureted motor, the better starting and idle quality alone are worth using a MSD-style ignition, even if I'm not sure the top end is better. It's not going to cure a points distributor though, I would still use a ZX distributor and  E12-80 module.

NOTE: unless you're running a turbo, I don't think there's any reason to add a MSD/CRANE ignition to a 280Z or ZX. In stock form the fuel injection and factory electronic ignition should give you excellent ignition performance. Carbureted and higher compression motors will see the most benefit from a better ignition.

COIL TYPES 

There are two auto coil types: oil-filled cannister and 'solid' transformer style (like the Crane PS-91). But I wouldn't get hung up over which is better, as they are essentially the same inside. The specs are what you should focus on.

• A coil is actually a just a transformer. It's + terminal gets a constant 12 volts to power it on. A pulse to the - terminal causes the windings to produce a boosted pulse out of the large center center tower. This is the common setup on just about every car over the last 100 years. A capacitive discharge ignition like a Crane or MSD sends 450 volts to the coil (instead of 12v). This is why a better ignition produces such a mammoth spark out of the coil.
  
• There are many performance coils out there, but most designs haven't kept pace with technology. Look in the Summit Racing catalog and you see several old-fashioned "performance" coils like the big yellow Accel. I doubt they have changed internally since the early 1970's when everyone used points distributors, not 10,000 rpm racing ignitions.
  
• So if you want a quality coil, buy one designed to work in tandem with a modern electronic ignition without a ballast resistor. The coil's "primary resistance" should be lower than about one ohm, but higher than about .40 or so. The lower the primary resistance, the more voltage it can convert. If you use one with a ballast resistor it will limit the coil's output.
  
• Most serious racing coils have very low resistance "primaries" (primary windings), and the resistance is lower than about .40 ohms. These coils can draw a lot of current so don't run them on a stock 280Z or ZX or a cheap ignition. The fuel injection brain supplies the 12V to the coil on these cars and can be damaged. A solution is to run a dedicated, separate 12V line to the coil + terminal.

• I originally used a MSD Blaster-2 coil(.73 ohms), and after a year changed to a Crane PS-92, which is rated at .20 ohms.  I really like
  the Crane's e-coil design, and when I accidentally cranked the engine with the coil wire off, the end of the PS-92 was covered with crackling blue fire. This coil is HOT! So I'm using a Blaster-2 now, but I think I want to go back to a PS-91.
  

280Z TACH INTO A 240Z

• I would recommend getting rid of your old 240Z tach. Vintage, but not designed well, they're inaccurate and start jumping around as they age: Replace it with a 1975-78 280Z tach.
• Put the new tach in the 240 metal housing, and swap the faceplates to keep the redline accurate. The needle pops off, don't damage it. A drop of rubber cement might be needed to put it back on. Don't use superglue or you'll never get it off again.
• Connect the tach's sensor lug to the negative terminal on the coil. NOTE: Make sure you reverse the power leads on the back of the tach, compare them before you swap for a reference.
• The little "loop plug" from the 240 tach should be plugged back into the wiring harness in the dash, otherwise the car won't start.
• If you have trouble getting the tach to work, a simpler solution is to replace it with a 5" aftermarket model like Autometer makes.

BALLAST RESISTORS  
Surprisingly, stock coils on older 12V points systems on every car were designed to operate with a max of 6-8 volts.
The reason is that on points distributors the entire voltage from the coil passes through the points, and too much voltage can burn them out.
So the ballast resistor was put inline with the 12+ wire to the coil to limit the voltage it puts out.

When you turn the key to start, the ballast is bypassed, and the coil gets a full 12V to put out a hotter spark for starting. Releasing the key inserts the resistor back into the circuit to preserve the life of the points. Why not design the ignition to use 12V all the time? Well, nowdays they do, but before 1977 or so that's the way all ignitions were designed.

This means if you buy a high performance coil and simply install it, the ballast resistor will usually limit the new coil's power output to nearly stock. So on a points distributor If you connect a wire across the ballast, it will route a full 12-14v to the coil and pick up some voltage, but it can cause the points to burn out more quickly.
Don't bypass the ballast if you have a '75-78 280Z. The 280 brain supplies the coil voltage, and removing the ballast can hurt it by making the FI brain supply too much current. 280ZXs supply a full 12v and don't use a ballast resistor.

SPARKPLUGS  
NKG plugs are the best I've used in a Z engine ~ smooth, predictable and long lasting. Bosch platinum are fine on German ignitions, but not on Z motors. I've been told that German ignitions evolved with a different overall resistance from coil to plug than Japanese ones. For whatever reason, most Z owners report misfiring and poor performance from Bosch. There's a big markup on "platinum" plugs too...companies know that dumb people think products with "gold, platinum, silver" in the name are better. Centuries-old marketing...

Also, be careful about using multi-electrode plugs, especially on high compression motors. I spoke to a NGK tech once, who said that the nooks and crannies on multi plugs can create lots of little hotspots and contribute to pinging. And since a spark travels the path of least resistance, it's going to fire only on one of the multi electrodes anyway. He said that multis are designed for the modern hemi-style chambers on Hondas, etc.

I think the best Z plug to use is the NKG BPR6ES-11, all year engines. Supposedly the -11 series was designed for better emissions/cleaner burn over earlier designs. Grassroot Motorsport magazine recommended the NGK ZFR6F-11 sparkplug for stock Z engines in an article a while back. It's a "V-Power" plug with a projected tip which extends out into the center of the chamber. Projected tips provide a more complete burn through the rev range, creating "free horsepower" and improving throttle response. They also simulate advancing the timing slightly by firing the mixture faster.

My 2 CENTS. Don't waste your time on Splitfires or plugs that use hocus-pocus. The plug only ignites the mixture, it doesn't burn it. So as long as a plug is firing properly, it's hard to do much better than that: use the plugs the factory chose. If you want to increase spark performance, concentrate on upgrading the ignition system instead.

I use NGK BP7ES-11 plugs, which are one step colder than stock.

PLUG GAP TIP
Some people recommend when using a high performance ignition/coil to open the plug gap to .050 (or wider). This is said to create a larger, longer duration spark to increase power. But on high compression motors conventional wisdom is to keep it at .045, because as compression goes up, it's harder for the spark kernel to start. 
Crane says to use .045 for "offroad and high-performance usage", MSD says .050. NOTE: going to .050 on a stock ignition/coil would only weaken the spark.

PLUG WIRES
I really like 8mm Magnecor competition wires. Very high quality blue silicone, they are "real" competition wires and put the other designs I've seen to shame. Grassroots Motorsports Magazine did a test awhile back and found that these wires added 1.5hp to a stock BMW motor(!) But despite what people think, performance wires don't actually "increase" horsepower. They simply work transparently to allow the coil's full output to reach the plugs consistently. These certainly do, with very clean output all the way past redline, they even smoothed out my idle. Nice. Don't use Accel yellow performance wires. I've tried sets on different cars since 1980, and they tend to corrode inside.

MECHANICAL  ADVANCE CURVE
This must be the biggest mystery in the Z world. I've been trying to get detailed info on what  curve works properly for years, but the  "authorities" seem to vanish when asked for details.
According to Haynes manual, different Z distributors have different curves. But apparently there were only two different distributor choices on L28s. If you take off the breaker plate, you can see "8.5" or "9" stamped into the top of the advance weights. "8.5" came on the manual transmission cars, "9" came on the automatics. The springs appear to be heavier on the 9. I've tried both and the 1981-83 "8.5" feels best on my 5-speed.

• This is a 442.com page on engine power-tuning, applies to all but V8s are the reference.
• Jason Gray has an excellent site with specs on all Datsun distributors: http://home.att.net/~jason510/
  

VACUUM ADVANCE
The dashpot that controls it is a big pain. It's purpose on the distributor is to react to vacuum from the intake manifold, and move the breaker plate with a little lever to keep the timing "optimum".  It adds it's advance on top of the amount the mechanical produces.
The settings in the dashpots are different from auto to manual trans cars, and from year to year. So this makes it very tricky using ones from the junkyard, as you never know if you get one with the right range. However, you can tediously chip out the epoxy in the end to uncover a screw-within-a- screw, (these adjust the vacuum-arm range). I've played with a couple but never been able to get these settings to work properly.

Unfortunately, after 15+ years, most dashpots are leaking, causing no advance and a big vacuum leak into the intake manifold.
Test yours by sucking hard on the hose going into the dashpot. With the distributor cap off, watch the vacuum arm pull in. If you "hold" the pressure, the arm should stay fully retracted. If it slowly leaks down, it's internal diaphragm is leaking/bad...and it should be replaced (it can't be fixed). If it doesn't move at all the dashpot (or hose) is leaking a lot of air back into the intake.
If its bad, temporarily plug the dashpot hose going INTO the manifold, as it will have been leaking air into the engine. It's better to run without vacuum advance, than to lean out the motor and burn a valve. Unfortunately, disabling the dashpot can make the car diesel @#$%. You can still buy dashpots from the dealer.

CHEVY HEI/D1 for 240Z
Using a HEI module was an older, cheap way of using a 1975-78 distributor on a 240.
However, the GM HEI is designed for the low redline of a V8 and is well-known for it's problems above 4,500rpm, even Chevy people hate them.
The ZX module is paired exactly with a L28 motor and 6,400 redline.

The HEI/ D1 was the first electronic ignition I used on my 240 a few years ago. But it made my 10:1 motor ping badly and never felt right. I suspected the spark was badly regulated internally, so I changed over to a D2 and E12-80 and the motor became solid as a rock past redline.
So while the HEI "works", it's a cheap redneck mod and I don't recommend it. The HEI modules sold in the auto store sells for $14, the Nissan module for $200, you be the judge.
Strangely, I've heard of some people trying to wire a HEI chip into a 280 or ZX which makes no sense: a 280 already has an electronic ignition.

 MY OWN SETTINGS?
I also use a 1981-83 manual-trans "8.5 degree" distributor, with the earlier E12-80 module on the side. After lots of swaps and driving I believe this is the best setup for a L28 with flattop pistons. I like to advance the distributor timing about 4 degrees from stock (12btdc).

I also use a MSD 6A and MSD Blaster 2 coil.