When I first got into the 74, I nievly thought I could simply rebuild the calipers and slap new rotors on it like any other car. Wrong.
Those nice 4 piston two piece calipers seem to be prone to harm from moisture in the system more than most setups, the cylinder walls get cruddy, the piston's dont move well, you cant hone them out cause then the pistons are loose, the seals start leaking from age and crud in the system, it rapidly becomes a mess. There's a reason why so many shops say "no way" when you bring a vette in or ask about brake work. Spend the money and get good rebuilt calipers, flush the system, check all the rubber hoses, mastercylinder and rotors. When there working right they are an absolute thing of beauty. Change the fluid regularly to avoid problems again. The rear rotors, I've been told, were balanced and/or trued to the rear wheel bearing assembly from the factory, and slapping another pair of rotors on there can suposidly cause problems. My solution was to buy a set with the replacement rear wheel bearing assembly that I needed anyway, I'm not sure what should be done when just replacing the rotors.
