Tom,
I think you're right.
Here is a link to Hammond's site with low to medium current power chokes. You are completely right, as I must have read wrong. 155J is rated for 30mA, not 300mA. The resistance of the original field coil is 1.06k ohm. The RCA schematic says total "B" current (probably B+) is 67mA. Do you suggest getting something that can do at least 100mA and use a high power resistor to make up the slack? Is it more important to match the inductance of the choke or the resistance?
Also, I was thinking about connecting an external speaker to the audio transformer and disconnecting the internal speaker to see if there is a difference. In fact, I'll do that tonight. But I wonder what the frequency response is of the original audio transformer. Back then, a wide frequency response wasn't required, even for prewar television or victrolas. I think the amplifier should have a fairly wide frequency response. I forget how to calculate the amplifier's bandwidth. Hammond offers audio transformers for general replacement of tube audio transformers and hi-fi replacements. General replacements go from 100Hz to 15kHz. Hi-fi replacements have a bandwidth of 20kHz to 20kHz, but weigh 11 pounds. :P Plus, I'll have to use a smaller speaker in any case, and possibly make some sort of bracket so it fits.
Thanks.
Jonathan