for a high boost 3rd gen the revs high? call me crazy but we are running a tricked 305 motor in my uncles SCCA car. We easily put down 450 on a mild track setup with stock bore and stroke. We use the 305 because we are allowed more modifications but also due to the smaller stroke it allowes us higher rev limits... we are running currently a 8.5k rpm redline...
but thats just what we did for a high rpm motor... now boost changes things alot... 350 and 383(stroked) parts are going to be way cheaper so id go that route... id say stick with a 350 with a nice forged rotating assembly and some good heads. Obviously stick with a lower compression around 8.5:1. Maybe put in a T76 if your feeling good.
Here is a link to my buddies LS1 with a single T76 putting down like 560 on 6lbs... hes looking for close to 1000 rwhp out of this setup
http://www.public.asu.edu/~nicolasd/