The C-4 won't last long behind your BBF. They don't do well with torque. We broke C-4 with SBF's, ended up running C-6s. A-1 makes an awesome conversion for the powerglide to go behind your BBF. PG are easy to freshen and there's alot of good used parts available if you need. I hated to but went PG's on my Fords.