1970 GTX, original 440/727. Has the old 284/484 purple cam. Stock compression forged pistons, ported 906's shaved 0.020", FBO ignition, Eddy intake, Holley 750 DP. I currently have a 3.55 but have very little low end power with this cam. I'm sure the torque converter is part of the problem but I plan on replacing that too. I drive the car 100% street with most of that in town. When I hit the highway I am content driving 60 mph.

So, with this motor what would you think about dropping in a 4.30 and a converter that flashes about 2800???