Well, I agree, although those numbers are a lot more difficult if you're running open chamber heads - say, if you swapped the poor-flowing 516 heads for later factory iron heads.
I'd also wonder if you'd get in trouble not having valve reliefs in the pistons if you start cutting on both the block and the heads.
I've posted recently that with a .050 cut on my Edelbrock heads, my 413's CR will be about 9.6 to one with pistons .080 in the hole. For a street car, that will be good enough - and a lot better than the 8.5 to one it has now with 906 heads even with steel shim head gaskets. If I absolutely had to have more than the milled Eddy heads will give me, or if I was starting from scratch instead of from a running engine, I'd just switch to a 440 block and use off the shelf pistons to build a zero-deck closed-chamber quench motor.
yea hard to get the cr with the better flowing open chamber heads. I heard Eddy is coming out with a 75 cc street head??
