I have a 68 Formula S 340, 4 speed with 3.91 rear. Engine mods are..... Ported X heads, balanced, 11.5 compression, Edelbrock Victor 340 intake, Holley 750 puddle dumper, Crower Street Roller (#31406 lobe center 112?, advertised duration i&e 290-294, duration @ .050 251-256, lift .550-.555.)...