you'd be spending a lot of money to dump a nissan motor back into it. The great thing about the small blocks in those cars is its a pretty straight shot and they're easy as hell. Mechanical fuel pump, no computer and drop in manual guages (autometer or something) then you can take a turbo 350 tranny, or a 700r4, whatever you prefer and rock it out with a 350, hell, even a 305 (a little cheaper). parts are readily available to do whatever you want to with it and they are cheap as hell. Go into any parts store and ask for a mild camshaft, intake manifold, carb, headers, you name it for a 350 vs a 300zx and see which one you get to leave the store with in about 20 minutes. It'd be worth at least thinking about. Plus....you can still drift it if you build it right.