Zed Head

Seems possible if you can work in that tight space. It might even be easier to get the pin aligned and the circlip on. Worth a shot. Worst case you just do what you were trying to avoid. Wish I had thought of that. I hated removing my console, Nissan made the wires so short it was really a pain to work with them.

McMaster-Carr has BSPT fittings. https://www.mcmaster.com/products/pipe-fittings/thread-type~bspt/low-pressure-galvanized-iron-and-steel-threaded-pipe-fittings/

Doing is knowing. Use Vise-Grips on the spring. My clevis pin had a round head also. Push it out with a screwdriver.

Remove the return spring from the pedal and it might be easier to get things in a position to come apart. It will also take any pulling force off of the rod. Also, you can loosen the locknut on the clevis and turn the rod with a pair of pliers to unscrew it completely from the clevis. Ths will leave the clevis hanging free on the pedal. Turning the rod while everything is together is the way to adjust it after installing too. Adjust it without the return spring until it is correct, lock it down, then put the return spring on last.

This might help after you take it apart - https://engineering.timken.com/engineering-tool/seal-search/ That's a weep hole. It lets the oil out before it travels down the inside of front cover nose to the pressure plate if the front seal leaks. By the way the steel front cover will fit the ZX transmission if you find problems with the aluminum one.

You showed the axle flange but not the backing plate. Check the backing plate for rub marks. Pretty common to get a slight bend in it. A hammer will fix it.

Sounds like the AAR is closing too soon. https://atlanticz.ca/zclub/techtips/aar/index.html

The parts manual shows only one propeller shaft for the 280Z's. https://www.carpartsmanual.com/datsun/Z-1969-1978/power-train/propeller-shaft And does show both transmissions. https://www.carpartsmanual.com/datsun/Z-1969-1978/power-train/transmission-assembly

Won't you have more heat with the headers? You'll be cooking that oil pan gasket. I'm sure a lot of work went in to designing and implementing that odd little piece of metal.

Hammer?

You'll want to block the heater core ports not loop them. Looping them allows coolant to flow back to the water pump without passing through the radiator. Carb cleaner will dissolve paint and swell rubber. I've found that WD-40 turns in to a gooey material over time. I hosed my distributor down and it was a mess inside when I took it apart months later. Seems like your dillema is whether or not you want to drive the car while you upgrade the parts.

My 76 original hoses split while driving and were blowing steam by the time I pulled in to my driveway. Don't forget that there are hoses in the cabin also. More to worry about. If you're going to replace them just make a slit lengthwise to loosen up the grip on the nipple. For some odd reason Nissan doesn't seem to have anything about the cabin heating system in the 240Z FSM's. It might be buried in a chapter somehwere but I can never find it.

The purpose of the tank on the early Z's might have something to do with the position of the hoses. The fuel probably sloshes pretty hard on turning, pressuring the vent lines. Without the tank that fuel could get pushed in to the vent line to the canister. The way that the system is illustrated suggests that it has a "drain-back" purpose. Plus they called it a liquid/vapor separator (#3). I'd guess that the vapor hose entry points were repositioned in later tanks. p.s. I'm not sure I was following what you were reporting in your previous post about liquid in the line. I thought it was with the #3 tank in place. . .

You won't know what it needs until you get in to it. The quality of the garage will be important. How you prepared it for storage will affect its rebirth. Did you dran the carb bowls? Add some stabilizer to the fuel? On the fuel tank, a lot will depend on the gas cap seal. I'd take site's advice and just crank it up on new fuel. It's carbs so not much to lose. See how it runs and decide if you have a huge project or just some minor work to do.

Have you seen distillation in action? Vapor moves man! Actually, the hotter the tank is and the colder the line, the faster you'll build up liquid. I'd actually be surprised if condensation was not happening.

Here's an image from the 1991 300ZX FSM, just to look at. No vent tanks, just straight lines. And a check valve.

Good opportunity to do a "will it run" pictorial. Let's see that fuel tank turpentine.

How about safety wire? Or a set screw. With thread locker. I think I already mentioned tacking it with a weld. https://www.cornerspeed.net/2014/bikeprep.php

Vapor condensation? It's what they do when they get cold. Vapors.

Circular leverage.

Thanks for the update on the springs. I didn't know that they came with a plastic coating. Also didn't know that you could buy them from TireRack. Also didn't know that they were so fragile. Are you saying that this is the second set that failed? At least they're still an option. There was a company that came out with new springs a few years ago but I think that they might have folded already. Can't remember the name but htere was quite a bit of discussion about them back then. Eibachs had a reputation for unpredictable ride heights. Many of the Z's that used them ended up looking like Gassers.

Watch this from about minute 10:00.

And, might as well ask since I'm here, are you saying that the Eibach spring or springs broke? Not trying to cause trouble, your writing implies that whatever it is is obvious to you. But you didn't really say what was going on and there's no broken ends shown for the Eibachs. The Eibach looks whole. Might just be me not knowing what I'm looking at but I've seen a few springs. I had some Tokicos in my car and a set of cut down stock springs.

Still confused. The black Eibach spring is clear. But now you've added another picture of what looks like a remnant of some other spring, intertwined with it. Looks like a single spring plus one. Two springs. What's the brown thing?, is the question.

I assume that was the early body style shown in your sig? Maybe that matters. I used the 280Z 4 speed shifter on all of mine, it swaps right in. Never tried the ZX shifter.