65 Valiant now gauges go full when ignition key turned or running

What do you mean by a "new converted instrument voltage regulator"? And do you have any more details about what the gauges were 'recored' with? We need to know what was put in your system, so we can see if it compatible with Mopar parts and your sensors. In looking at the Instrument Specialties site, the say that they recore with VDO cores, which are probably not at all compatible with your Mopar sensors. Mopar sensors are pretty low resistance compared to others.

» Gauges & Clusters Instrument Specialties

Do the following: Remove the wire from the temp sensor on the engine and measure the voltage there when the key is in RUN. It should be either 5v or a pulsed voltage (depending on the meaning of that new converted instrument voltage regulator). This will tell if the regulator is doing what it should for Mopar sensors.

Does the fuel gauge still go up when the headlights are turned on?