Fred,
I was gonna put an original radio in my '54, however, I'm running 12 volt so I needed a voltage reducer. I managed to find a working radio on ebay and I hooked it up to a battery with a voltage reducer and tested it. The voltage reducer got really hot and I was thinking that I didn't want something that hot under the dash. I mean if a wire fell across it it would melt the insulation! Anyway, the radio made my decision easy as it up and quit working after about a ½ hour of testing it. Anyway, I ended up re-selling it on ebay, I figured since it had been working someone with more knowledge then I might be able to salvage it. So, being that '54 and '55 1st have different radios then the other AD trucks, and nobody makes one of those custom classic radios for them, and the one's I've seen that were modern conversions, (in other words AM/FM guts inside one of the original radio shells), were like $500 - $600, I decided to buy an old non-working radio and I tore it apart and made a false face for the dash and then I mounted a more modern 12 volt AM radio that had a built in speaker up under the dash. I turn it on and off and tune it by just reaching up under the dash. I plan on eventually getting an AM/FM radio to mount up there and replace that one. Dash look like it has the original radio but I don't have to worry about that hot voltage reducer. Anyway, that might be a way to go if you don't want to struggle with an original radio. With that said, if someone did make one of those custom classic radios for a '54 I might go that route as those are about $250 or so if I remember correctly.
