How to build a 13 second 340 Duster

My son has Eddy RPM heads on his 9.5:1 comp. 360 in his 70 Dart. He's running a 780dp Holley on a RPM intake, not sure of cam specs. The subframes are tied and the rear springs are moved inboard with 3.55, 8 3/4 and a 4-speed. With 255 BFG TA's his best 1/4 is an extremely traction limited 12.90 at 112. Personally, I think the aluminum heads would be the way to go.