Dashboard voltage regulator for 1964 Dart 170

This thread should help...
dash gauge question
You can use that part house limiter as shown above but... ground it to the car chassis. The instrument panel isn't grounded before it is attached to the dash with those few screws. Even then its not a good ground. This is also stated in the linked thread.
The limiter/regulator doesn't have to be behind the inst' panel or dangling from the wiring.
If your part store would exchange for a limiter for the E-body/challenger/barracuda it will have a bolt ear on it so you can mount it anywhere under the dash, just like those cars. You'll simply need longer wires to hook it up ( just like those cars).