Note that when I say depending upon the filament voltage, I mean that you will need to ask Hagaman whether the unit provides six or 12 V for the filaments. Then choose the tube accordingly as regards 6FQ7 or 12 FQ7. When I say the 6CG7 would require re-wire, I am essentially saying don’t use it unless you are capable of doing the wiring or you have a tech who can do it.
I also forgot to mention that if you stick with the 12 U7, I would recommend Amperex bugle boy, again assuming you are certain that they are what they say they are.
I also forgot to mention that if you stick with the 12 U7, I would recommend Amperex bugle boy, again assuming you are certain that they are what they say they are.