The stock CUCV VOLT gauge is actually a 12 volt gauge with a resistor across the back.
so if you've converted to 12 volts can you remove this resistor so the gauge will work again?
mine is just a dash ornament right now
Yes, you can use the stock Gauge to read 12v, if you have converted to 12v only. Your options only limited buy your imagination!
In your case(without looking at the schematics and determining if this is the simplest choice), I would remove the resistor on the rear of it, and connect it(+ terminal) to a keyed 12V tap, in the fuse box(there are a few of them). Your negative side to a good ground.