John, I got my 235 up to about 9 1/2:1 compression by shaving the head as much as it would go. So it is possible. I did not notice a huge bonanza in power improvement though. In fact, I don't think it was noticeable to me at all.
Weak is weak, maybe just a lesser degree.
The biggest improvement I saw was in carburetion. Put some better carb or carbs on it, with a split exhaust, and that is power improvement that you can feel. All that the rise in compression did for me was just to require a higher octane gas. So I don't think that was enough to justify the cost of machine work to do that. But let's see what others think...
