[Arran]

Ron;
  I was thinking that a transformer from a 40-180 would work, but the B+ is only around 180-200 volts in those models, that was how they got away with using a type #84 tube and how the later versions got away with a 6X5. Your set seems to use about 250, which with the current draw of the 7B5s, was likely running the 6X5 pretty hard. If you could convert the set over to using a transformer with a 5 v rectifier winding, that would be the best solution for the long haul.
  If you could fit any r one of these on the chassis it would be winners, a 570 volt HV winding is sort of odd, though I did find one with that:

https://www.edcorusa.com/xpwr008

Or this one which is even closer to the original, add an extra $1.54 for 240 volt line operation.

https://www.edcorusa.com/xpwr014

This seems to be the closest with voltages, since it has a a 570 v HV winding, though more expensive then the second one, and probably overkill for amperage, you could use a 5U4 with it though and kiss the wimpy 6X5s and silicon diodes goodbye:

https://www.edcorusa.com/xpwr049

Regards
Arran