Upgrading stock 1971 318 heads

When milling for compression during a rebuild.... much more than .010 requires cc'ing the chambers 1st or you really have no idea how much you'll need to mill in order to end up where you want.

If it's a deal of head gasket changed and nothing else, mill .010 and put it together... but if you have a target...you need to know where you're shooting from.