One thing you might consider is the MAD Electrical ammeter bypass. IIRC, it's pretty simple to add a voltmeter to the cluster in the ammeter's position. When I did the bypass on the Charger I had already added a mechanical oil pressure and voltmeter to the car.
http://madelectrical.com/electricaltech/amp-gauges.shtmlAnd here is a thread on FBBO about doing the "fleet bypass" so that the ammeter remains functional. Not entirely sure about this one as I think the general consensus is that the gauge itself is a weak point also.
https://www.forbbodiesonly.com/moparforum/threads/ammeter-bypass.65337/Tim
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