My 69 GTX clone is a 505. I went with TrickFlow 270 heads and a good roller. Motor not yet installed, but it made 713 hp/709 torque on the dyno. I am looking to run low 10's and will be street driven Has a gear vendor OD.

67 Coronet 500 9.610 @ 139.20 mph
67 Coronet 500 (street car) 14.82 @ 94 mph
69 GTX (clone) - build in progress......