I think that was exactly the opinion that I gave earlier. You are not going to get quench with a 906 unless you use those silly reverse dome things. If you have no choice they are what you should use, but you have options. The 12:1 CR guys are not using reverse domes, but you would have to. Diamond can get their 12 cc dish piston to about 620 grams. You should be able to get away with 10:1 CR, maybe a little more with what I suggested earlier considering on how late your intake closing will probably be.