Some things are searchable, but a quick opinion can be given easilly enough. Mind you, this is coming from the guy always harping on people to search
First off the VG30DET is an Australian engine mostly. Where are you located, Timmer? You need to update your location information on here. Go to My Controls, then Edit Profile Information.
Really, you're talking about the VG30DE, which is he DOHC non-turbo, and the VG30DETT, the DOHC turbo engine, both which are from the Z32 300ZX (1990-98). It has been done, although also in Australia. Level of difficulty is probably very high, and the fit is extremely tight. There's a pic on here somewhere, it might take you a half hour of searching, but look for "VG30DETT" and make sure to display results as posts and not topics, it shows a little preview window of each post found.
The thing about the SR or any four cylinder swap is that the crossmember is totally different, so you'd have to get a four cylinder S12 crossmember. That's not all that hard to do.
I STILL suggest going with a remote mount turbocharger system on your VG30E. There is a thread by a guy called mc in the Club-S12 Garage section who did a remote mount turbo... go check it out, plenty of pics, and it runs nicely.
That's what I'd do.