It was about $40+ per rotor on rockauto. It should be 5x4 as they quote it's for A-bodies between 68-72 (only sbp vehicles).

That's awesome! More than likely,it's just the rotors, and you will have to take both your new and old rotors to a machine shop and get the hubs pressed off the old rotors and pressed onto the new rotors. If they show up as unicast rotors/hubs in small bolt pattern, that's even better, as they are less prone to warping.