Need Advice Installing IVR into 65 Dart Cluster

Not just any ring terminal will make a good connection beneath the pizzy stamped speedy nuts. Home Depot and others have the 10-32 hex nuts and internal toothed washers ( just like what is on the amp gauge. Another 2 dollars to spend). A ring terminal followed by a toothed washer and hex nut on top of the speedy nut is a better plan. The gauge stud is plenty long enough.
I dont understand why people add a solid state outboard regulator and continue to supply 12 volts to the fuel gauge after its no longer required there ( except for the fact that RTE told them to open the fuel gauge and disable the OEM limiter). The switched 12 volt wire in the round harness connector serves nothing more than the OEM limiter. Better to take that wire out of the round harness connecter and route it directly to the addon regulator.
If the 12 volts goes only to the addon regulator, electric tape is placed on the back of the fuel gauge to isolate that gauge can and OEM limiter from chassis ground,,,, opening the gauge to disable the limiter is not required. A 3 post gauge that does not get 12 volts and is not chassis grounded will only function just like any common 2 post gauge. 12 volts aint going there, 5 volts can't bleed to ground through the remnants of the OEM limiter.