Aluminium adapter for coolant sensor will mount on a head bolt and have a 3/8 pipe thread for a GM coolant temp sensor. Megasquirt needs engine temperature for cold start enrichment. Some air cooled installations have used oil temp but it is slow to change. This should work as the squirt is very programmable for stuff like this.
Used thermal paste as there is no coolant. Adapter has a two step bore with the deep part just a little larger than the probe part of the sensor.