Btw, I noticed you posed the same question in another thread. If you're looking for a precise number you won't get one, since the stock combustion chambers vary in capacity and the deck heights also vary. Since you have the air cooled heads and not the water cooled version, at least you don't have to worry about the water jacket issue.
IMHO the best approach is to first get the deck heights right, then check both heads for combustion chamber volume and have each one set to your desired volume. In other words, blueprinting versus "close enough for government work". We have some head experts on this site, some of whom posted in your other thread. They didn't give you an exact number to mill the heads for a reason.
Jerry