What donor vehicle to get disc brakes setup from for 72 swinger.

I once saw on this forum that you could use parts from a much newer vehicle to convert a 72 dart with drums to disc brakes. Would anyone know anything about this? I know I could just spend like $1500 for new parts but honestly the money is just not here at the moment. I have a lot to fix on the car and 1500 on brakes at the moment is just not at the front of the line.
Depends on what you mean by "much newer". 40 years ago that statement was true but these days the parts cars are not much newer, they are roughly the same age. You used to be able to go to a wrecking yard and grab the brakes from a FMJ car for a quick disc brake upgrade. If you were smart you would also grab the 11.75 rotors and caliper brackets from an R body as well as a set of 15 inch rims and you were in cop car heaven. Find a set of big drums for the rear, an anti-sway bar off another car, and maybe get lucky and find a Feather Duster to part out while you were at it. But those days are long gone. Best bet these days is to call up Doctor Diff and buy a kit.