https://www.rt-eng.com/rte/index.php/RTE_limiteR
Here is a premade setup. There is also info out there to build your. Yes I kept the gauge and it works with the new regulator. Had to take it apart to bend the contacts out of the way. In essence you’ll be converting to an external limitor. Even if you build your own the info given on that web site will help you out with the wiring.
https://www.rt-eng.com/rte/images/e/e7/InternalLimiterFixUsingIVR3.pdf