Controlling an aircraft instrument

I have an old aircraft instrument, it maybe a turbine temp indicator. It has a 3digit LED display and a moving coil meter. I want to use this in my flight sim project. When I turn a potentiometer I want the display to go from 000 to 100 and the needle to move from zero to full scale deflection. I have thought of using a digital voltmeter IC and adjust the voltage to it, but wondering if anyone has any better ideas or suggestions?
Thanks

Chances are that the primary sensor is a type-K or type-J thermocouple. mV from the sensor makes the instrument indicate. Look up the thermocouples on the web, and generate a few mV using a 1.5V battery and a suitable resistive divider.

Thanks Mike for the quick reply. The unit is crammed full of components so no way to find where the i/p is. What I plan to do is to remove everything from the unit except for the display and moving coil meter and then somehow power those directly to give what I want....if you understand what I mean!