Does anyone know if a VG30DETT and transmission will fit an 87 maxima? How much modification would be nessary?

Only one way to fit it in : massive chassis restructuring. Either the front end needs to be lengthened, or the firewall needs to be set farther back into the car. You're also going to need to look at cooling issues, etc...but, hey, if you got the green, you can do anything...

Maxwgn is right. Basically in all reality, there is no way. Also the next question is...is it really worth it? If you want to run boost, what you should do is think of 3 options. Supercharge a VG30E, or get a VG33ES, Turbo a VG33E, or swap in a VG30ET. The easiest of the 3 options maybe the VG30ET swap. You will still have to do some modifications, and it is definately not a weekend project. VG33E is about the same boat as the VG30ET swap, just got to find a motor, a turbo, and build it. The VG33ES option is going to be the most difficult because it hasn't been done. Plus the VG33ES has a roots type blower, which is mounted atop the engine. That will cause some severe hood clearance issues. I personally think the easiest way to do it is to go with a gear driven supercharger like the Vortech V1. You would have to fab up a mounting bracket, idlers belt etc. There seems to be a little bit of space for it right above the A/C compressor, but you will have to relocate a bunch of gear and what not. Either way those are your options.

S