wiring question

I was hopping you would keep the ammeter face plate.

That looks great.

You could get switched power from the same wire that feeds the IVR. It is switched 12v.

Also any screw that screws into the metal housing will be ground. You can check some of the indicator bulbs, one side of the cir board will go to a pin the other will go to ground.

Post a photo of the back of your cluster I'll point out each.