I just bought a bbc for a reasonable price and it has a set of BB2 plus heads on it. I pulled the heads off and the block is o-ringed, block filled an inch from the top and the bore mesured out at 4.380. I was told it was a 501 but something don't sound right. Also the heads had water in them and busted both ends on both heads, I'm sure they can be fixed but what else should I look at on the heads for damage. Thanks YB.