I think you will get a 10:1 ratio if you use the Mitsubishi DOHC NA head (early versions). Using a Hyundai will start to push it up to 12:1. And depending on what you're doing with the engine in regards to cams you will more than likely need to fly cut recesses for valves to prevent fouling on the piston deck. I have thought about going twin cam at some point by using a Sonata head and pistons, Ford EDIS ignition set up and...bike carbs. I am a fool for old school but getting my cake and eating it too is a looong way off (I should get my current engine assembled and running before anything else lol)