C20 3/4 ton brake upgrade question

[binford]

Dial in the manual brakes and they work, but after one hard emergency stop they need time to cool. I found on my 68 they replaced the master cylinder with one for power brakes. Once I installed the 1" piston vs the 1 1/8" they were like night and day. No more standing on the pedal.
FYI hit a big puddle and you have no brakes, well until they dry off. So I learned to ride the brakes a bit as needed.

x2 on flushing the brake fluid. It should be replaced every two years to prevent rust at the slave cylinders