If you use a control stat from a boiler it would be best fitted at the bottom of the rad as the max temp is normally 80c.
Going off on a tangent, I have a sensor directly in the coolant on the head side of the thermostat with a digital gauge (not an NG).
I have found that the 82c stat normally opens at around 90/92c then the temperature drops in under 10 seconds with the stat closing at 82c and the cycle starting again to control the temperature.

Thanks for that, i do know with boiler stats the common Ranco types,fitted to 90% of pre electronics and thermistor sensor control ie twist and click are available as 90, and 100.They are identical construction to most sold as electric fan controllers.
I use an electrical temp gauge as well, and the 88 water stat opens approx 88 , and when i tried it in a pan on the hob with a laboratry thermometer it opened at 88, i wouldnt be surprised if the quality varies a great deal.
So many pattern parts that are supposedly OE quality are Shi*e
what do you think would be a good temp to have my rad bottom tank fan switch at, im going to try an 88 on 76 off one from a lancia.