i second what russ said...if you are going to rev it over 7000 rpm on a regular basis,then i would steer clear of it,but like russ said,at the least get some block filler...if you are going to build a 393,you would want to start with something thicker,especially if you are going to build a higher rpm combo...russxr67 said:Why don,t you ask them if they did a sonic check on the block before they bored it.This would have verified suitability BEFORE any machine work can be done,especially on a 393. If they can,t tell you than I would tread carefully . I would consider that any engine shop worth their salt would be able to confirm that the block is up to par considering their reputations in this dept.Clevelands are known to be thin here and a test would have either confirmed that the block is a suitable candidate or not. FWIW, I,ve struck water on a routine 30 over bore . For a 393 buildup you may have to sonic check a few blocks before you find one that is good enough.Oh, and I would want it to have some sort of block filler as well.