[Jack21]

This may, or may not be the answer you wanted but...

Got the fan sender, connector, and fan control relay from Ron Francis Wire Works.

The fan sender, a 180 deg unit, went into its own drilled & tapped hole in the intake right next to the temp gauge sender, and right over the water jacket outlet in the head. The on & off temp values came with the kit. I remember checking it on the stove with a pot of water and a meat thermometer before installing it, but don't recall what the values were.

The power in side of the relay takes +12v off the power grid and has its own circuit breaker. Power out goes to the fan. The control side takes power off ignition, and completes the ground through the fan sender. Also have another complete the ground through a dash switch for getting stuck in traffic.

With 180 thermostat, gauge stays right at 180. In stalled traffic, I use manual override when gauge goes to 200 - 210. Fan will cycle on and off otherwise.

You could install a temp warning light, but that's what the gauge is for. You could use a hotter sender in the thermostat housing for a light.