My advice would be to buy a good block........which would likely eliminate the chance of you being here in a 150 more passes with the same type pictures, asking for opinions on what to do.

You guys can talk about detonation, balance and all this other stuff. Doesn't change the fact that the blocks are weak there and any 30 year old block to be used as a race block is a serious crap shoot. Even if it is out of your one owner, 67 model grandma car that only has a few thousand miles and never driven over 30mph............Still don't mean a damn thing..........it's a stock block.