How much can a set of 360 heads be shaved, what effect would this have on chamber volume and what might be the increse in compression on the typical 8:1 360?

I have seen them milled in excess of .125. These heads have been running on a dirt tracker for a couple of seasons. Rule of them is .0048 cut to = 1 cc volume. Law of diminishing returns applies. Personally I have gone .070 with no problems. For every .010 it is recommended to take a .0095 cut off the intake side of the head to get the intake to mate up correctly. I have not found this nessessary up to about .040+. It is not recommended to cut the intake surfaces. Cutting the intake side of the heads brings everything back into spec's and either or can be used down the road on other applications without further milling or wondering what to mill off what.