The easiest swap would be using the transmissions that came with the truck, which are the early style FS5R30A. I believe all of the early style had the starter mounted near the engine block whereas the start is next to the transmission on the Z32 setup. From there you could then bolt up the same flywheel and clutch setup the truck uses.To use the Z32 transmission there's a chance you'd have to take a hammer to the tranny tunnel to make room for the starter but getting it on is relatively easy. Pick up an NA transmission, an 89-91 Maxima flywheel, either a Maxima or 84-86 300ZX clutch kit, and a 90-96 300ZX throw out bearing and it will work out pretty well.
Driveshaft wise, if you go with the early style you could just use the a driveshaft from a 5-speed truck but if you go with the Z32 transmission you'll probably just have to go full custom on the driveshaft. As far as driveshafts lenghts go... I'm not too sure on the truck as I've not seen the measurements nor have had a chance to measure one. Its pretty easy though. If you decide to go with a custom shaft you can measure from the tranny outlet to the differential flange and a driveshaft shop could throw one together for you. They can also give you the exact point to measure from each spot. 

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