273 build idea......

The bore does have a bearing on compression, but nothing as much as stroke. A short stroke engine is more difficult to get compression up. You can build a domed piston 383 with closed chamber heads and only end up with 10.5, yet the 383 is a relatively large bore engine. Since its stroke is almost the same as a 340, even though it has a large bore, it makes it more difficult to get high compression figures because of the short stroke.