[rotorwrench]

I would recommend the solid state constant voltage regulators or runtz type CVRs for each affected gauge rather than use an old style chopper CVR for the whole power circuit. Those things make the instrument needles move around a lot more than they need to. The little runtz type CVRs are available from a lot of sources and there are even U-Tube videos on how to fabricate your own. A resistor makes heat and robs the system of power. A dropping resistor needs to be protected from anything that can melt or catch fire.

Ford Used the chopper type constant voltage regulators from 1957 well up into the 60s since a lot of instruments were made to function on voltages lower than 14-volts. The lower the voltage, the less chance of problems was likely what engineers had in mind. I had an old 64 T-bird for many years and the gauges always wandered around in service. Those old CVRs didn't really keep the voltage constant at all. It just fooled the loads into feeling the voltage was constant.