What's more interesting is how many didn't understand this. Nobody ever needed to open the gauge to disable the limiter. That started with one person on a Imperial forum web page many years ago. Vendors of solid state regulators simply ran with that info rather than investigate this application/assembly.
Just isolate the limiter from ground. The 12 volt wire serves nothing else, take it away from this limiter as far back as harness connector if you want, and route it to the replacement limiter or regulator. If the fuel gauge is good it will function like any 2 post gauge. Lift one of those and look for any chassis ground. There isn't one. Only current path is through the gauge.
Please note, if the replacement is a solid state like 7805 regulator,,, Make damn sure that thing is chassis grounded. Without a ground it will pass the 12 volts straight though and out to the gauges. Some of the more expensive packages have ground fault protection built in.