383 Build - Help!

I don't see an over bore stamp on the piston tops, so I will assume it's standard bore. With a .039" gasket, and a .020" below deck, (might be more), the +5 cc valve notches make 9.06 to 1 compression if the heads are indeed 78.5 cc's. Nows the time to cc some stuff before it goes together, in case you want to have some things milled.