[codefox1]

I agree with all, but suggest the 50 ohms would probably work out under most circumstances. I would further add that a 50 watt resistor would be better, given the sizew of this set, and it will get hot, so what I would do is locate it away from everything else, use an insulated heat sinking bolt, and play the set for a while. If the B+ is within range, and the performance is good, you're set.

The bucking transformer soloution is more elegant, that is, if you have a suitable filament transformer that you want to donate to the radio. But be careful where you mount it, lest you introduce interference. Been there.