[Arran]

I don't see why you couldn't work on the brand Z first, followed by the RCA, the 6S52 is basically the same chassis as one would find in a table/mantle model since it's a six tube chassis. It looks like the cabinet used to have a dark strip down the middle of the pilasters, and on the beaded molding just bellow the speaker grille, you can easily spot a refinished set online if everything was refinished on a monochrome. A guy that claims to have a refinishing business did this with an RCA-Victor model 281, posting pictures on the ARF, the legs were darker then the body of the cabinet, and had a black stripe on each leg, he redid them all in a medium brown, along with the rest of the cabinet. Your best bet for getting knobs would be to attend some swap meets, the Renovated Radios ones are plastic made to look like wood, alternatively you could play the fleabay lottery for originals, buy some wood reproductions (though I'm not sure about whether they make 1936 Z knobs) or contact someone like Mike Koste, or one of the other second hand knob vendors . With regard to table radios, you will find a few in short order, in fact one of our members would probably be able to supply you with as many as you require, he's out on Long Island.
Regards
Arran