Weston Station Meter
You probably DON'T want to set it up like it was "back then". Those were the bad old days when we didn't have wall-warts to make handling mains voltage safe, etc.

I think you have a great idea to use a wall-wart.  I would use a 12V wall wart and a ~100 ohm pot to "calibrate" the meter reading.  And then you could replace that incandescent bulb with a nice array of LEDs powered from the same wall-wart.

I would probably throw a 1000 ohm resistor between the source and the "top" of the pot so that I could use an ordinary pot (not a more rare, costlier high-power wire-wound pot).