[Arran]

One of the interesting attributes of tube equipment is that no electrons will flow without the tube heaters energized, so if I wanted to shut off the front end of the radio the easiest method would be to shut off the tube heaters. I plan to do this with a Canadian Westinghouse set I have that has a good 6U5 magic eye tube, I'm going to add a small bat switch in one of the existing holes in the chassis, so I can operate the set with the magic eye turned off, you could easily do something similar with this RCA, shut off the tube heaters from the 6H6 on back, which would also save .9 amps of current draw on the heater winding of the power transformer. At the same time you could use the heater winding, which is no longer supplying the front end, to power the Blue Tooth module, and whatever it uses for an audio amp. I'm not certain whether impedance matching will be an issue or not if you feed it into the grid of the 6F5 through the volume control. Since this is a console it may be easier mounting all of this on a panel installed near the back of the cabinet, but remember to twist the heater wires coming out of the chassis, or use a shielded cable for the audio coming out of the module to the phono terminals. The switching is the next problem, one for switching the power from the heaters to the Blue Tooth module, and one for switching the audio between the radio front end, and the Blue Tooth module.
Even with all this added I would still recommend changing the paper caps in the front end of the set, even with the tube heaters shut off there will still be B+ going to the tubes, at various points, but I think you were planning on this anyhow as it's cheap insurance.
Regards
Arran