Well, back in the day when these engines were newer, the hotrodders would take them .080 to .125" over. But since these engines are so old now, rust and corrosion have eaten at the water jacket side of the cylinder wall. Its best to have any block sonic checked for wall thickness when boring above .060". Cheap insurance before you go ordering special pistons, rings, balancing, boring, etc, just to find out you've struck water or warped a cylinder.
chip
