Don't waste a dime on the stock 4A heads. Mine measured about 86cc and they have a horrible exhaust port. Some 64 to 72 Olds 330(around 64cc) to 350 heads(68 to 70cc) with 2" or 2.07" intake and 1.625" exhaust valves with the bowls opened at a minimum. Better flow and a good compression bump. This will bring your current 7.5 to 8 to 1 compression to around 9 to 1, depending on how far those pistons sit in the hole.