Yes it will definitely fit since it is the same motor in the 89. The Z31 model was from 1984 to 1989. The Z32 model (2nd gen 300zx) was from 1990 to 1996. (barbie car commercial)
with considerable time, maybe? the only thing they kept the same from the z31 to the z32 was just the VG30 short block the engine was changed to a DOHC engine making it considerably wider, I have owned an 86 turbo and I currently have a '90 N/A. I wouldn't dare try fitting the VG30DE into the z31.
You might have a problem with the orientation but it will work.Here's a list of engines seen in a z31, http://www.az-zbum.com/modification.engine.swap.shtml
It's possible, in fact here's a 2JZ-GTE in an '88 or so z31, click on the engine link.http://www.az-zbum.com/modification.engine.swap.shtml
They're all the same from 90-96, you're golden
yes it can.
although possible, it is not recommended. The actual cast engine block is the same however, the intake manifold and exhaust manifolds are to wide to fit into the z31 engine bay. So it is possible but would take a good amount of custom fabrication. I'd recommend an sr20 or rb series motor swap. considerably less modification
yes with heavy modification
Yea, a 300ZX's engine can fit into a 240SX although there might be some need for adjustments in the engine bay.
yea but you have to change the mounts and the radiator but why would you do that just turbo it
fit a twin turbo engine
No. Not without custom brackets. If your gonna put Z32 seats in a Z31 I would spend the money on a nice Recaro racing seat, or other aftermarket seat. Good quality company's like Recaro will make the brackets for the seat to bolt right in. And they look good too.