Need some technical help guys.

[Olden Days]

Yes I was using calipers (Mine was an original disc dual wheel truck but rotors were shot. original rotor was tall and looked simular to the 74 up dual style but some what smaller (thinner and not quite as big around.) the rotor part was the same size as the c/20 rotor and used the same calipers as the c/20. Switching out the spindles and calipers seem like it might work ,as I considered that myself. I just never took it that extra step to see if in fact it would.
I hope that wasnt too convoluted to understand,