[njsteve]

Here's something interesting. There are stamped letters next to the bores. Are these for selective fit piston assemblies? "S", "M", and "L" for small, medium, and large? The 1975 350 block in Gramma's car had similar stampings on the deck surface as well, only they were the letter "P" next to each bore. The machinist said he has seen these on other Pontiac blocks over the years.