Back in December '19, I ordered adapters from Scarebird (https://www.scarebird.com/). They make adapters to put disc brakes on a wide assortment of cars. The kit includes adapters, some minor hardware, and a list of brake parts (rotors, calipers, hoses) that you will have to buy.
The kit I bought is for '63-'73 Ford Mustang, Falcon, Mercury Cougar, or Cyclone with 15" or larger wheels. This is the kit:
The parts I had to buy were '68-'69 Mustang 11.25" rotors and grease seals, 1990 Chevrolet Celebrity calipers (and pads), and '79-'85 Cadillac Eldorado front brake flex hoses. I used the wheel bearings that were on the Ranchero.
It was a fairly simple installation. There's a bracket on the Eldo's brake hoses that have to be removed. Here's the right side: