E36 - 320 Race Car: Monster Hybrid with RB26DETT or 4G63

Hey guys!
I have just embarked on the strage and wonderfull quest of building a full out racer. At the moment I need to follow N2000 regulations which means i can't do anything about the engine. It's a one make and model race based on the E 36 - 320.
However I'm considering on what to do with the car once the season is finished - a fully stripped and caged racer is not exactly road legel.
I have been thinking of swapping the engine and have some fun that way.
Anybody have some experience with swapping a 320 E36?
Most interesting ideas I've had sofar would be a swap with a RB26DETT from a R34 GTR or a 4G63 from a Mitsu Evo 8. Another interesting way to go would be to turbocharge the rebuilt but stock M50 engine it's got now or swapping with a S50 M3 engine. From my researching so far I've heard many good things of super or turbo charging the M3 engine.
If anybody has a word of advise or comments on my idease please make some noise. Need to bounce my ideas off somebody else to decide which way to go.