JRichard, I have the same delimma as you. I was told my EGT gauge may not be accurate. The thermocouple output is in DC millivolts. You would need an accurate power source for an output to check your gauge. This would allow you to test your gauge from min to max readings. The problem is, this type of power supply is not common or cheap. I spent some time years ago in a research laboratory and used this type of equipment daily. Also, you MIGHT can use a good DVM to check the output of your thermocouple, if you can set the meter to read millivolts (Mv). Sorry I could not be of more help.
Ronco