When building my car many years ago I had difficulty in finding a dual temp switch to fit the M22 boss in the Hawk radiator and opted ( wrongly it seems) for a VW variety.
With my recent over heating issues I decided I needed to search again.
For those in the need I can but suggest you try T7 Design who have an array of both dual and single temp switches.
I have just ordered one that has ranges 92C down to 87and 88C down to 83 having been advised by V8 Developments that a Rover engine temp should be kept lower. E.g they felt that once over 90C you would be fighting a battle.
I had always been switching the fan manually as soon as it went over 90 but this makes it automatic in case I don’t see the temp rising in time.
Peter C