Missed on this combo?

I'm not going to go into a big story here but that combustion chamber can cause problems if you shave too much off.
Now i have said that. Get some clay and roll it into some string and then trace your combustion chamber. Then lay it on something flat and measure how big of a circle you have. now .7854 x bore x bore x stroke so let's say you clay string circle is 3 inch so .7854 X 3 x 3 x let's say a .020" head cut. .7854 3 x 3 x .020= .141372(CI)X 16.387=2.3166 or 2.32 CC.