How about converting my Alty to RWD and putting in an RB30? :E
SFR just did a 374whp 315wtq single turbo 3.5L Altima. Pretty sure that would smoke 95% of the cars you are considering purchasing. DO IT.
Actaully, I have been corresponding/negotiating with Tim @ SFR for the last 2 weeks on exactly that.
My car might be going to SFR in the spring for a twin throttle body intake manifold. Tim is very well respected in the G35 and Z community.