My Crown half cut had a temp sensor in the radiator.
It's a normally closed contact type and operates at around 90 degrees.
As it's NC it works the opposite to what you want. It turns off when it gets hot.
I use a JAYCAR thermo switch which is adjustable cost around $21.00 and I had fun building it. I know nothing about electronics and built it in an hour and it works well.
The switch can operate at whatever temp you want to set it at. You can also control the off temp. The switch has three outputs. Two NO and one NC so can make it do different things.
One advantage of this unit is it doesn't need the sensor in the water jacket. It uses a thermo-couple which I slid under the end of a radiator hose outside the clamp zone so it's in contact with the pipe. The thermo-couple doesn't get wet which means the cooling system has one less place to give trouble.
JAYCAR sell quite a few usefull products. I'm working on a fuel mixture gauge that gives a digital real time read out with a bar graph for quick checking.
JAYCAR have Australian, UK and US Websites
www.jaycar.com.au www.jaycar.co.uk and
www.jaycar.com They do mail order and will post internationally.
By the way I don't have any connection to JAYCAR I just find their product range good and the instructions with their gear is excellent. You can build it all with a small soldering iron only but a digital multimetter saves having to learn resitor codes and saves erors.