Hi Paul my engineering friend across the way at work told me what the thread was in the pump itself something BSP I took a photo of it and included it on our earlier chat. The wire are used was any old wire taken from an old Renault 4 wiring loom. You will find the little LED light inside powered by those little fine wires is very bright so you might want to consider a lower position for the dial? Until you get your adapter it might be worth
while trying the wire on the existing Jaeger temperature sender located on the rear nearside of the head. I have a strong suspicion this will actually give you a reading as opposed to an on off switch . On my car I've connected this to a warning light. So I have both the dial and the red light to tell me of high-temperature