need to raise compression w/o new pistons

I find out that the head cc is 65 to 71 (seems like a large variation ) but there is a .2 cc reduction for every .oo1 milled from the head. I can always shim the rocker shafts to bring the rocker geometry back in line and to keep from preloading the lifters too far. I have access to the tool to flycut the pistons if needed (most likely will). Have no idea how much is the average when zero the deck -if I use .015 and plug it into the formula I posted it gives me an approx compression ratio of 10.9 which seems to be a bit much for (approx. .020 cut on the head and .015 on the block --which may be way too much )