I bought a manual flywheel for a BBB from a board member and a clutch/pressure plate. It turns out they are the small pattern on the flywheel, same as what is in my 350 car. My question, as listed in the title: Is a 10.5" clutch stout enough to handle a mild 455 of about 425-450 HP? Or do I need to go 11" for a 455? I really don't intend to race it but I want it to hold up to spirited driving with aggressive throttle and shifting.
I would go with a 11 inch. You can't have too much clutch if the tires bite,hook goid and you're in the throttle hard. I have a fairly new 11 inch hays borg and beck for sale cheap. $50 plus shipping. Message me your email and I'll send you pics.
To be honest, I'm just accumulating parts right now in case I decide my 350 car isn't what I'm after. The flywheel was the only thing I was lacking from a 455 swap. On the borg & beck, I've always heard they were quite stiff on the pedal.
I have an 11" Ram clutch (2 face) behind a pretty mean BBB, with 3:42 final and it gives me no troubles. (FWIW, I have had less trouble from the 70's on with diaphragm clutches. ) A 10.5 should be no trouble on a mild build street car. But if you're buying new, going larger is pennies on miles and worth the peace of mind.
