Milling of a 810 casing W-2 head

Its cold and i'm thinking of the 360 i may build in the spring. Its flat top piston .005 in the hole and .030 over. I have a set of ported W-2 heads and would like to know how much i can safely mill them. Anyone with experience? I don't believe they have ever been milled on the chamber side.


Deck the block instead. Stick the piston out of the hole. If you take that much off the head they don't seal very well.