C body stuff will not all interchange. Only '73 c body spindles use the same upper ball joint as the '73 up a body parts. '74 up c body upper ball joint are bigger. Rotors are 11.75", but the bearings are different and they'll only fit c body spindles. Bolt spacing on the lower ball joint is different. Spindles are 5/8" taller, so the geometry changes ( not necessarily bad, but it does change the geometry). And the 73 up c body stuff uses pin calipers.
More trouble than it's worth IMHO. If you want 11.75" brakes, use the f/j/m body stuff. Same for the spindles, the f/j/m spindles provide some positive geometry changes, but they'll bolt up to 73 up a body parts.