360 Bore

.030 is listed IIRC as maximum fatory allowable on anything newer than 1980. .040 is no big deal for stock and mild builds. If you plan to make more than 400hp, or really work it (pulling/towing, racing, whatever, then .030 is always the safest bet. 318s can go .090 if they pass sonic. You'll never see a factory 360 block that can go safely to .090. Different casting cores=different thicknesses. smaller than .020 may be hard to find pistons for too. .030 is normal.