Well I thought the same about a .030" overbore. Surely enough meat for that with our dragster. So I did not bother sonic checking the block. Well the end result was this. The cylinder wall was roughly 2X the thickness of a Pringle! This was a 69 HP 440 block. I too was more concerned with the mains than the wall thickness of the block. Apparently I should have checked the cylinder walls too. As for the question at hand. I would make sure you can get a good ring for the finished bore size. Pistons are the easy part, they will build the clearance into them when manufactured, provided the info you give them is accurate and the bores are round you should be good.