[Arran]

They probably refused to ship the chassis and speaker alone because they don't want to be stuck with the cabinet. Some people part out consoles but the top value bits are normally the knobs, dial, and the dial escutcheon, depending on make or model, and everything else ends up being worth less the more it weighs. I would just post an ad in the classified forum looking for a chassis for a 38-7 T or XXX, but have a look inside the Radiobar cabinet to see what speaker you need to ask for there.
One thing I learned when looking for old radio parts is that it sometimes takes a while to find what you need, for example it took me 18 years to find a suitable replacement chassis for a Canadian G.E E-81. To be honest I wasn't looking for continuously all that time, I was only aggressively looking for maybe 5 years, and found one in the form of a chassis from a U.S built RCA 7K. But I don't think you will have to wait quite as long to find a 38-7 chassis, Philco was the top producer of radios in the U.S market during the 1930s, and given that this is a 6 tuber they sold a fair number of them.
Regards
Arran