pontiac was the only one out of all the gm companys that always had fully machined combustion chambers... my stock 6xs have 2.11 and 1.77 valves. Now isnt that bigger than any stock sbc? besides maybe an LT or LS engine(i dunno about those)
w/ a little porting and screw in studs, these heads have awesome power potential...
these heads are on almost every pontiac engine i've ever seen that's 76 and up ...at least till 79