[Arran]

Again I don't think a custom made transformer would have been necessary in this case since the set uses your typical 6.3 volt AC tubes and a 5 volt rectifier, the main difference might be in how much voltage the H.V winding puts out. Most are a 350-0-350 affair but some are higher, others lower, it really depends on what audio output tubes they used, how much they drive them, and how much current is needed. In most cases you can find something off the shelf that will work, especially with the vertical mounted style transformers. Where you might need their services is if you had a radio with a type #50, those were 7 volts, but needed 500 vdc to really work, or one that has motor driven tuning and a winding for the motor, I think they were 24 vac. There were also some oddball sets that used combinations of 6.3 volt AC tubes, and the older 2.5 volt style, I think there was a Silvertone and a Lafayette brand radio that did.
From what I remember reading Edcor has an engineering charge for custom winding transformers, but if they find they already have the specs on file they will refund it.
Regards
Arran