yes, you can put a chevy LS1 V8 in there... http://www.grannysspeedshop.com/
(edit maroon snuck in while I was typing the novel below)
would be MUCH more car then a 370z though.
I have done the power thing and let me tell you, its not the way to start. I have a mustang and its too much to take on a track, I just autocross it. Starting with something like an NA rx7 or you dub (im just not much for FWD) is the way to go. The more power you have the more depressing it gets to drive on the street. If you do more then poke the throttle you are breaking the law. With a lower power car (in my case a BMW E30) daily driving is much more fun because you can use much more of the cars capability. On the track the difference is with the power car it all becomes about putting down the power, with the other it becomes all about technique and line and finesse. If you eventually get to the point that you want alot of power thats fine, but get on the track with something slower and learn technique and finesse FIRST and you will be much better off in the long run.
The other thing is that with more power typically comes more expense. More power means higher speeds, means more brakes, means more (and bigger) tires. Tires for my E30 are literally about HALF the price then for the mustang. Is it more about you and having fun on the track, or is it about impressing women and your friends? If its about fun the lower power has a lot more bang for your buck. (then again, I could be wrong, I auto-x a mustang and the grass IS always greener...)