[Arran]

Mid production model 90s are common enough that you should be able to find the original parts that are missing, if not a complete chassis that was less molested. I would have to review that schematic to see what you mean with the filter caps, but it wouldn't be the first time where someone confused the connections of the filter caps in a pre war radio. Typically they assume the filter caps are both grounded to chassis like they are in 90% of the radios built from the 1940s onward, but they can't really do this on power output tubes with directly heated cathodes, like #47s, #45s, etc. due to the way bias has to be obtained.
Regards
Arran