One more follow-up to the gauge saga. I connected the NOS temp gauge to the sender and found that it pegged out on the hot side before the engine was at normal operating temperature. After a lot of experimenting with a variable resister, I found that by adding a 24 ohm resister to the sending unit wire, my gauge now shows the gauge at the 1/2 way mark when the engine is at 178 degrees. Engine has a 180 degree thermostat.
So I now have a working gas and water temp gauge in the original factory gauge cluster. Next test, how long will it stay working?
I have not removed the aftermarket manual gauge yet. Although it's not hooked up, I think I will leave it for now until i am sure that the electric gauge stays working.