As Rob and the others mentioned, the FIRST thing to so is have the block sonice tested. Secondly, why do you want to go .060 over? Does the block need that much to clean up the bores, or is it just something you would like to do? I was always of the opinion that you only over-bore as much as is necessary at the time of the current build. If you do it this way, there's room for another bore and rebuild later if need be.