Re: Proper GEARS needed!
A bigger cam will reduce low end power, but increase top-end power. That's just how it is.
Your '64 trans doesn't have the switch-pitch converter, so a higher stall one will get the engine more into the power band.
Modifying the distributor for a quicker mechanical advance as well as more initial advance will likely boost off the line performance, I'd suggest starting there. Either find a 2x4 or a Dynaflow distributor or have yours modified.
Shorter rear tires will have the same effect as increasing the gears. What size tires do you have?
(1)'66 GS Astro Blue, 13.41 et (2)'66 GS Saddle Mist, L76 Q-jet option, 1 of 132 (3)'66 GS Flame Red, Calif car (4)'66 GS Silver Mist, 4 speed (5)'66 Special, Flame Red, 300 (6)'79 Turbo Regal, 14.1 et (7)'65 GS 4 speed 'vert