If all the gauges are acting up, it is likely you IVR (Instrument Voltage Regulator is the common name I believe). I don’t know where it is on an early A, but they are available aftermarket.
If the gauges are pegging, you are likely in danger of damaging them.
The fuel gauge IVR would handle all but the ammeter. The fact that is acting up is another issue. The older (55 years in your case) cars have likely had a LOT of hands in the pie, so fixing things like this will simply take time and patience.