VG30E's are one of Nissan best engines in my opinion...they are pretty bullet proof and very torquey. We got them here in 300ZX (Z31) and 300C (Y30) otherwise know as a Cedric. The Cedric version is only 150bhp but it's in a car that wieght near on a ton and a half. I know a stock 300C wagon will run a low 16 second quarter which considering the weight is pretty respectable. The 300ZX version here is 178bhp. I have a friend with one fitted in a Datsun 810 (200B) and it goes well. The V6 is probably a bit more torquey than a KA24DE and a tiny bit heavier but one thing for sure..they sound awesome with open pipes

I've never know VG's to have any problem other than occasional noisy lifters, and running faults due to lack of maintanace (usually plugs as they are awkward to change so they get neglected). I have seen AFM's pack in working on them but generally they are very reliable units.

In the picture above the engine is still fitted with the Z31 plenum and exhaust manifolds, one of which crosses behind the heads. Over there you'd be able to get the S12 version of the V6 which has seperate down pipes each side and a different plenum. With that setup you could probably get the engine back much further.

As for the mounts...I figured there would be enough room to reinforce the frame rails and make mount brackets to accept normal engine mounts so you would have to solid mount it. I swapped the Z31 oil pan for a Y30 one and it cleared the stock B310 crossmember fine. I could probably get you one of those if you wanted.

The trans is basically the same as S13 and S14's use and is pretty trouble free. Avoid the Z31 turbo trans though as that's supposedly not that great. I think they have a reasonably tall 5th gear on normal 5 speeds, a bit like KA's. The auto's have ludicrously tall gearing.