Which heads are better 1970 Mustang 302 heads or gt40
I have a 1970 Coupe with a 302.It was a daily driver until some valves started pinging. So i pulled the original motor out and i had a '76 302 that fairy new so i stuck it in. I also added a performer intake, 500 cfm carb, and headers. But my car seems slower now than before. so i would like to do a head swap because i understand that '76 heads are extremely weak ( goverment emisions) Would i be better off to get my original '70 heads redone, with a hotdip, pressure check, ect ect, or would a good set of gt40 or gt40p heads be better (i understand my headers may not work with gt40p)????
1970 coupe 302 C4
2007 V-6 5-speed, shaker 500, premium wheels ECT ECT