[Arran]

 I think that I would just reveneer both shoulders of the cabinet with some book matched pieces of French walnut, any cut will do but maybe straight cut, sure they didn't at the factory but you might as well do it right now that there is a reason to fix it. Also the missing vertically grained veneer above the dials and speaker looks like orientalwood veneer, the stuff they used to use on the front arch on Philco 90 and 70 cathedral cabinets. The sides look like quarter sawn French walnut veneer, something Philco really liked to use on many of their cabinets between 1937 and 42, notice how it has a very straight and parallel grain. Speaking of Orientalwood veneer I should really see if I can locate some, same with some Sapele or Etome (whichever it is), the latter two are African hardwoods look much like mahogany but not quite.
Regards
Arran