How do you judge when it's time to bore? I have an a 350 apart now. I wasn't going to dig past the heads but a couple of the pistons rocked slightly in the cylinder. I figured OK rings so I pulled em. There is no decernable ridge or cylinder wear except in one cylinder. It looks like a tiny bit of something (maybe a sand grain) got between the wall and piston. If you run your fingernail across the scratches you can just barely feel it. I'm going to replace the pistons and rings but I'm not sure if these scratches warrent getting the cylinders bored. Thanks for your help. ---Rich