Can '64 Dart Temp Gauge Be Adjusted?

My gauge reads right at the bottom end of the "operating range" scale most of the time. Infrared temp gun on the T-stat housing reads ~184, and rgw tenp sender read ~181. If I let the car idle for a whille after driving it the gauge goes up about 2 needle widths, and the t-stat housing reads ~190-192.
I'm planning to pull the sender and using my camp stove put it in water as I bring it to a boil, monitoring water temp and marking the gauge reading.