Possible suspension swap

Ordering parts is simple when you know what you have :) I don't see a aftermarket kidapter at the upper ball joint so you do have the upper arms with the large ball joint, along with spindles, calipers, pads, hoses, etc.., for 73 thru 76 disc brake parts.
I doubt the entire K member and/or steering linkage was swapped. How to tell... Pre 73 model K is closed so the stabilizer bar went around the front of it. The 73 and later K has opening where a stabilizer bar threaded through the middle of it.
There are ways to add OEM or aftermarket stabilizer bar around the K member you have, even with those later model disc brakes.
For now we will assume you still have pre 73 model center link, pitman arm, and idler arm.
Duster, Demon, and Dart Sport stand separately from all other a-bodies in a lot of ways, especially body wise. Much of the mechanical will interchange though. Good luck with it.