I agree with Pat. For heavy duty use a Ford top loader or Mopar 4 Speed. If this is any indication of what the serious racers use, Lakewood makes Chevy bellhousings with a Ford or Mopar bolt pattern so you can use one of those transmissions behind a Chevy. I have run a Muncie behind 2 425+ hp 427s. One in a 4000 pound Biscayne and the other in a 3500 pound Chevelle. They both survived in a street/strip car, but I was not running them flat out in serious competition. I was using what was in the cars, if you are going to go shopping for a transmission, might was well get one that will last a long time. If it meets your needs, you might also consider a Nash 5 speed.

my $.02

Pat