There are c-4's that will handle over a 1000 horse. look into performance automatic. not sure of web addy. A c-6 takes more power to turn because of its rotating mass. I know of a few running c-4's behind 557 cubes with no problems on a drag launch.
For 460 info, this is the site you will want to visit.
There are alot of intelligent people on there. Alot of engine builders.
http://www.network54.com/Forum/85220/
there are alot of tranny gurus there also. Do a search on the c-4 or any 460 questions. You'll find alot.

dave