Brake pedal course

Hello.
On my '63 Dart, I recently installed a power brake assembly; the 1967 period with the dual-chamber master cylinder.

The issue is the pedal course being too low to the floor; less than 2 inches, which I find yields to a disconcerting driving.

I tried adjusting the pin between the booster and the master cylinder. That did not work: 1 and a half additional turn will have the shoes to drag heavily. One turn and a half less turn has everything working fine except for the pedal diving too low once again.

My suspicion is the booster belonging to the next generation needs a longer rod under the dashboard between the pedal and booster to accomodate to the earlier generation. While the travel of the pedal would be the same, at less it wouldn't dive so low.

Any feedback will help