Hi Connor...I have a very similar engine combo. It came with the car and I have been making the best of it while trying to build another engine. I have similar pistons that are TRW 2293. It has about a 20cc dome. fast68plymouth suggested that I check the volume of my 906 heads and I came up with a chamber of about 92cc. In all my compression ratio turned out to be about 9.8:1. This is what my numbers looked like in the calculator that I used. Yours might be similar.