No companies I know of sell new tubes any more, although they can be found sold by individuals occasionally.
You will probably have just as much luck using a curb find consumer TV tube really.
Those 7000 series chassis are super tolerant of a fairly wide range of yoke resistance/inductance values.
Later models of cheap CRT TVs have relatively lower resistance yokes and frequently work great as donor substitutes.
I would go looking for an old 19" TV and get out the multimeter.
And we miss ya Ken.