If I was bored (& had plenty of time) which is the story of my life I would get a guestimate on the CC's of 906's milled 30 & an average HG thickness & the supposed zero deck & plug it in the the KB pistons calculator site (its a fun tool) & there there should be a site or chart somewhere on the SCR that would produce those kind of numbers then see what piston dome it would have to have to achieve that. that'd keep ya busy till you confirm with another gauge and or open it up (first I'd borrow a borescope). Keep us updated. EDIT At least I would see what dome/CC's would be needed to get 10:1 which is what they came up with & they did mention zero deck so likely they did measure everything.