Having worked at Ford Dealer in 80-81, I can tell you that the number one problem with those calipers was the e- brake. Before you go to the hassle of finding cables, make sure the e-brakes will apply and release. Rebuilding them wasn't hard, getting the e-brakes adjusted to work correctly was. If you have to have them for safety inspection, I get it. If you don't and the hydraulic portion works, wait a while and upgrade when you get the funds. You will be several headaches ahead to upgrade.Looks like a Lincoln Versailles. Could be a full size Lincoln Continental or Mark, but they were very wide. The Versailles was very popular for building street rods at one time. It was a fairly narrow 9" Ford with disc brakes and they were readily available in salvage yards. This would have been in the 80's and 90's. This has changed and last I heard, brake parts were very hard to find. Except for the brakes, all the other parts are just regular 9" Ford.
You may wind up having to swap to a newer set of rear brakes, since that rear end has not been made for at least 25 years.
Once you do manage to get the cables off, Lokar may have cables with the ends you need. Give them a call. You may have to send them a picture of the existing cable ends.
EDIT: I just checked and the Versailles was only made from 1977 to 1980, so those brakes are over 40 years old. It's most likely true that the brake parts are not available. With only 3 years of production, there is not much of a market for the specialized brakes.