i had the same car a few months ago

you can do basically anything as the bay is huge, practically nothing is "bolt in"

a 4AGE w/ ITBs or 4AG would be good, but for a little more you can just get a SR20 motorset

or if u wanna go cheaper/more bang for the buck/and slightly more original (which was what I was about to do, but had too many non running cars at the time... so i just sold the car) is drop a GM smallblock 350 V8 and throw on a supercharger or some small twins... thats a BEASTLY car... the car weighs around 2k so thats incredibly light
it might be a little cheaper but you'll pay for that in labor and hassle, but the reward will be oh oh oh so greater