Cool, just got Findm-Keepm's variac today.
It's a bit of an odd piece. The scale on it goes from 0 to 120, but the wiring diagram shows that it's set up to go to 140. So, there's pencil marks around it at voltages that must have been important at one time. So, I think I'm just gonna put a
volt meter in the case along with a cord connector from a computer power supply (I have plenty of those to scavenge) and a power outlet.
It was lovely how the power cord crumbled away in my hand...