Moving the pivot point on the brake pedal

It would be about 100000000000000000000000 times faster and cheaper and easier to get a smaller master. "Liability". Personally I would not screw around with the pedal, unless you are comfortable with mechanical design and certified/ x rayed/ etc welding

On a side note (my 67 is still apart, sad....) when I had it running, it has a Lincoln Versailles / Ford 9" rear with factory disk, and 73/74 Duster Demon factory front disk. "Just for fun" and to see where I sat, I punctured the residual pressure valves in the master and used the stock factory drum master. I'm 73, now, but even then I had knees/ legs issues, and I can stop that thing just fine. Not that hard to slide the tires the bit at 70+ It gives me a rock hard pedal at less than 1/2 pedal travel