[hound dog]

Yes, it can be rebuilt as a world class T5. But, different input shaft, different gears, different synchronizers, and maybe a few other items I didn't mention. The best avenue to take is find someone who rebuilds T5's and they may have old transmissions lying around and perhaps they could swap some parts for you or maybe trade the whole tranny for another one. If you're going to build an engine with over 400 hp I'd forget about the T5 altogether and look for a toploader or tremec.
h dog