Uh, are you really running C-body brakes?
Meaning, you changed out your spindles to C-body spindles and re-drilled them because the lower ball joint spacing is different between A and C bodies? And you're running 1973 C-body spindles, because those are the only ones that use the same upper ball joint diameter? And of course they're 5/8" taller too.
Or are you running the later B/R body 11.75" brakes which bolt right on to 73+ A, and F/M/J spindles?