On the plus side, the TFA-2004 output transformers are truly excellent and worth a large chunk of change, especially the nickel core for 300Bs.
On the minus side, the AC filament power will produce a bit of hum and the Steve Bench hum cancelling circuit helps only a little.
Harder to assess:
* You could make a DC supply for the filament, if your power line voltage is at least 120v. Design details were posted on the old Forum, back in the day...
* The voltage rating on the power supply capacitors and rectifiers has very little margin - especially if your power line voltage exceeds 120v.
* You could probably implement the Paramount soft-start shunt regulated driver, though there are no specific instructions for that adaptation. This is the biggest technical improvement we have adopted since that time.
* The old-style 6" by 10" chassis plate is a bit cramped, and has no IEC socket so the power cord is soldered directly to the circuitry. I know some folks cut a suitable hole in the wood base for that.
