I am putting a 350 into my '84. What transmission do you want to use? From what I have read here, the stock R-200 rearend will be strong enough to handle about anything you want to drop in. I removed the V-6 and the engine wiring harness. When the v-6 is out there is a lot of room for a chevy. The biggest prob seems to be with the left exhaust and the steering. I'm using block huggers, but I've heard that the stock iron manifold will clear the steering. Height is tight, but the engine will fit under the hood. Hood clearance is a problem for me , but that's because I'm running a vertex mag and stack injection, which is tall.
SteveR and Darthmentos are doing this swap, and have pics posted somewhere on here. For the most part, it doesn't seem to be too hard to do. Use the search for 300zx. I'll try toput the pics I have in my personal gallery. If there are any questions I can help you with, just PM me.
joe