'73-up brakes with smaller UBJs?

Hey guys, I recently picked up a front disk brake setup supposedly from a '76 Dart which was being run in a '66 Barracuda. Came with spindles, rotors, hubs, calipers, and pads all assembled. However something strange the seller told me, he was running the brakes with his older ('72-down, "small-ball-joint") upper control arms and replacement smaller A-body ball joints. I haven't been able to try to mock this up for myself since I sold my original '70 UCAs but has anyone else here successfully used '73-up BBP front discs with '72-down UCAs and ball joints? Would this cause any weird alignment or geometry issues? Guy said it ran fine with no problems but I'm just a little hesitant... and I want to know because he threw in a pair of new-in-box 'small' upper ball joints with the brakes, so if it'll work I'll start looking for '72-down UCAs.