hello,
any formula for milling heads to reduce chamber cc's, 78 cc's now would like to go to 70, after 6 years putting togeather 540 (stage IV 285 chapmans)
gary

i don't know what the amount is for that head but there is a way to determine depth of cut if you have the tools.

you need to level the head side to side and end to end precisely (machinist not a carpenters level). have both valves installed and sealed, spark plug, then with a accurate burette fill the chamber with the desired volume of fluid. take a depth micrometer set it on the deck surface and turn the spindle down until it's close to the surface of the liquid. then slowly turn it until the liquid jumps up onto the spindle of the mic, take your reading and that is the amount needed to cut.

http://www.mopar1.us/mill.html