I was way off. I went back and looked at a picture of the RPM heads, and the quench pad area is alot smaller than I thought (I was thinking chamber was more like the victor heads.)
From photos it looks like the quench area is only about 15% of the chamber, so if you had the estimated bore size (4.4"?) minus the 15% (3.74" equivlent bore?) then a 0.010" cut would be 1.8cc, and each cut would increase the quench area resulting in slightly less cc's (maybe 0.1cc) removed per cut? With these numbers it would take a cut of about 0.110" to take the 84cc heads to about 65cc?