Thank you George and Dave.
If you know of any headphone amps and/or owners that would like to try these adapters out, please get in touch with me.
I would like to make these and other tube adapters available to any who could use them.
These particular adapters were built to sub a 6SN7 for a 6H30. The 9 pin base is the same as the 6DJ8, 6922, 7308 series of tubes.
If your filament winding can handle the current, swapping in octal bases will give you lots of options for tube rolling.
Another use I can see is using an EL34 in place of EL84 in amps. The amp would have to be re-biased to use the bigger tube, but it should not be too big a problem.