In the example above i assumed a bore size of 3.5 and dome size of 2.75 so insert your own values. Squish is the differance of dome and bore.
The equation might seem like it's missing a factor of Pi, but if you work through the calculations, you'll find that it cancels out and becomes irrelevant. Earlier today i was working with area values and Pi (3.14) and got all goofed up. Im exhausted just thinking about this stuff.