1973 Duster 9 inch brake upgrade questions

I don't think the 73+ drum brake parts changed from 1972, which is why you still have 5x4" bolt pattern. Probably the same spindle, which is what the Scarebird kit cares about. I even doubt you have the big upper ball joint, though shouldn't matter. People here say the factory just kept using 72- parts until they ran out of front drum parts.