you need a O1A-10889 heat bulb adapter ---its listed in the parts book for when a later engine is used to replace early engine with temp bulb in the waterpunmp to adapt to the pipe threads in later heads
And if there are issues with the temperature bulb seat in other brand heads /blocks the temperature bulb adapter for a 60s MG midget works, I just used one on a Packard head that the seat had rusted away but still had threads