The paint chart in the resource area doesn't show black. I think it was a special order
Paint Codes - First Generation Monte Carlo Club (firstgenmc.com)
In my opinion if the rear wheel well has to be replaced, I would think there is more rot that you can't see. For that kind of money, I would look elsewhere but that's just me. Good luck
If you change the lights out for gauges you will need a different printed circuit. They should be a brown wire that runs to the coil. I'm not sure if that's all you would need. Someone else will chime in. Good luck with the upgrade.