I dunno but my cast piston 8:8.1 440 with stock 906 heads, summit 488 cam, RPM intake, Proformed 750DP, headers, 175k convert, 3.91's went 12.08 @114 at 6psi of boost off a SN-2000 supercharger. This was in a full steel 3850lb 67 coronet. Probably had more in it. Your's should have at least second more in it, more boost, bigger cam, less drag on the engine (no belt) cool, drop it in and lets see the boost gauge jump.