Ralph; I just finished doing a radio with that tube, and I got lucky and I found a chassis for sale with that tube.
It was 80 miles away, but I got it
You said ”someone plugged in an 80”. The 6H7m tube has more pins than an 80,so it would not fit.
. Do you have the schematics for the radio you are working on? What model is it?
Dan in Calgary.