Tunnel ram 440

I know you said you didn't want to remove the heads but couldn't you replace the stock heads with a set of 915 or 516 heads and up the C.R. These heads are plentyful and cheap; along with a thin head gasket you could up your C.R. 1 1/2 points. Just a thought. Have you checked with Hughes Engines? They make cams with less duration but with more lift than other cam makers.