Always been told 71-74 360s are thicker. Or the lower the casting number the better the casting. ? never seen anything proving one way or the other. Have seen late 70s blocks bored .060 over w lots of meat left.
you hit the nail on the head with the lower the casting #, the better the casting. The reason being is that the mold will be less likely to have core shift with the first few pours versus the last few. I believe a mold is only used 6-8 times then they chuck it for a new one. Someone feel free to correct me if I'm wrong, but that is what I have researched over the years.
