Those are the later open chamber heads. With stock 2 barrel pistons and todays thinnest head gaskets you probably will end up wit around 8.5/1. The open chamber heads are the same heads used on the 68-71 318's. The #302 heads are closed chamber and will bump your compression a half point or so plus they flow better. 273 heads like the #920's (you want 1966 and up) are the same valve size as the 318 heads but are closed chamber.
