Learning here, so bare with me. But how does smaller bore relate to compression? Are you talking compressing psi, or talking ratio? Can you elaborate?
As I said, TRYING to learn lol
Look at a 340. 10.5 at the top of the bore. 273 has a dome to get the same Compression ratio. Really a mute point on the street, since you can't run 10.5 on pump gas. I shoot for 9.0. I'm not going to worry too much about compression as much as flow. Race engine is another story.