what dual quad intake are you running?now really up in the air,,,64-65 have smaller heart shaped combustion chamber,66 commando heads more open chamber,,,would the closed chamber bump the comp.ratio up even more than 10:5-1?
I have the 920 heads, cut down stainless 1.88's to 1.84, 1.60 stainless exhaust. bowls blended, radiused, smoothed exhaust, rounded around the guides. They flow 166.9 cfm at .450 of lift with 116% port velocity. Plenty for the 273 combo I'll be running.
