Milling heads is not a very efficient way to raise compression. Let me give you an example. Using the compression calculator on the United Engine website, you can see that it takes a bungload to make a 1 point difference. Using 72 cc as a starting point with the head and 6 cc for the pistons I came up with 7.7:1 compression. That's probably fairly close. In order to move that compression up one full point, I had to decrease the cc's of the head to 60. That's 12 cc's. That's also a .072" cut on the heads. That's a lot to have to worry about intake alignment, pushrod length and valve train geometry. I don't know where different head configurations come into play. It does not make a difference what style of head you have or what shape the chamber is. "X" amount of cc's equals 1 compression ratio point. PERIOD. it is a mathematical equation. It will work out on paper the same as it would on any given engine. I've seen people try to make the comparison using different head shapes and chambers and on and on. It's the same kinda equation as 32 ounces makes a quart. It doesn't make a hill of beans difference what shape the glass is. Never has. Never will.
