hi mark,
Some where on the meter, sometimes the very lower part of the face scale it will state the FSD mA or uA of the meter.
I'm assuming that they are moving coils meters.
Once you know the FSD current you can calculate a series resistor to scale it for a Voltmeter, these are usually FSD = 100uA
or a ammeter and calculate a Rshunt resistor, these are usually FSD in mAmps.
You can remove the front scale face and use 'lettra-set' numbers to remark them.
If you cant find the FSD marking its possible to use another calibrated meter, in series, with a battery and series resistor to measure the FSD.