Crooner, that is so cool!
Beautiful radio, too -- I'd like to have one similar to yours someday.
As you well know, one of the big drawbacks of restoring these old Broadcast Band radios is that there's hardly anything on the air that's worthy of them. I think that many others are going with setups similar to yours, to get the sounds that are appropriate to the vintage of the radio.
Here's a
kit for an AM broadcaster I came across on a website just the other day.
This guy offers the same unit assembled and tested, and also a cheaper kit. I wonder if these things work any better than the FM transmitters that I've tried in the past?

They probably do, since there's no stereo to worry about.