The 16.5's will clear the calipers, so will 16's.
15's will too, with a sh*t pot of grinding, which I don't understand why anyone would do.
Little pricey
https://www.performanceonline.com/63...-deluxe-8-lug/
A guy sent me this about doing a disc swap back when I was asking.
OPTION 1: get the spindles only from a 71-72 up truck, get new ball-joints to match the year of the spindles, new calipers or rebuild, turn rotors or buy new rotors, new bearings, throw it together. Use the donor upper ball joint, taper is different on upper, lower is the same. Use the donor lines, you'll need a disc/drum proportioning valve, don't skip this unless you enjoy changing calipers a lot! The control arm bushing are a bear to remove, they screw in/out and the lower arm bushing bolts have a small weld bead on each. Not sure if it was factory or not. Retorque to 230 ft/lb.
OPTION 2: get a whole crossmember from a later model truck.
I'm sure someone will chime in and give you more info. Good luck.
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