Very - quickly as I have dial-up at home and the pictures won't load. So I'm trying to get this in a few minutes. The two treadle machines are 27's and most parts are available. Sew-classic has the slide plates and bobbins. The shuttles (if missing) might have to be gotten on the auction sites. The one with (H1534346) is Tiffany decals - my favorite. The Modernage Super Deluxe Precision is a 15-clone and probably quite a decent machine. Many clones and even my 1972 Necchi-Alco has that kind of plug. One plug should come from the motor the other from the light. One end of the 'outlets" that those wires are plugged into goes to the foot controller and the other gets plugged into the house power. I think the parlor cabinet is a model 21. I don't know if ISMACS has it listed (probably) I'm sure the Smithsonian has some images in there trade literature, but I don't have the information with me for a link. I don't know about setting the featherweight in and sewing with it in a parlor cabinet. I suppose you could. All could be refurbished and/or restored to function as they were originally intended. It kind of depends if you want to put the time into it.
There are lots of posts about cleaning all these things up and back into service.
Janey - Neat people never make the exciting discoveries I do.