On our .060 over we found .080" estimated on the bottom of the thinnest bore. Some parts were .100" thick yet. I don't know how accurate these tests are but that's what a reputable machine shop told us it was. It was too banged up to continue to mess with it so we scrapped it. It would be interesting to take a .060 block and drill it and just see exactly. I imagine core shift was all over the place.