Hi

I have a 1981 RX-7 with a SBC and a T5 that I built a couple of years ago. Unbelivable takeoff power, like a streetrod, but it can go around corners at speed also.

A good place to get info is the V8 rx-7 forum. There are alot of guys who have built or are building those things that post regularly. Its also nice to post about a v8 rx-7 without getting flamed by rotary purists (avoid rx7club.com like the plague).Here is the link: http://www.torquecentral.com/forumdisplay.php?f=11

Also take a look at granny's speed shop.
link: http://members.tripod.com/~grannys/rx7.html
Grant makes kits for numerous engines into rx-7's. His kits work best for "simple" v8 conversions.

If you want to go to a more complicated but much better swap, Brian Hinson sells a kit to install a LS1 into 2nd and 3rd gen rx-7s.
http://www.hinsonsupercars.com
This is the way to go if you don't want to disrupt that 50/50 weight bias.

Good luck,
Dave