[Mondial]

Considering that these are valuable radios and you want to keep them as original as possible, I think you made the right decision.

The glass enclosed ballast tubes also have another advantage. They are designed to regulate the voltage going to the filaments so that regardless of the line voltage (within reasonable limits ) the tubes are always given the proper filament voltage. An additional advantage is that the ballast tube limits the filament surge current at turn on so that the tubes last longer.