If fluid is equal (volume & pressure) LR & RR, I'm thinking it's in the brakes themselves: Wheel cylinder binding/not releasing Springs or mounting not allowing shoes to back off drums. Could even be the order in which the springs are installed, had that happen once. I have a '57 Chevy FSM from when I had one in the '70s, if that helps.
Tip of the hat for someone dailying a Tri-five, BTW. But to be honest I'd want to upgrade the braking system.
