I snapped my autometer temp sensor in the head as well..but luckily it capped itself off..so i bought a radiator adapter hose fitting to put the sensor in..has been fine for 2+years now.
as for the head,You can always try to find an adapter a brass male/female..male larger to go into the new larger tap then female side smaller to fit the sensor into.
but might take some searching and trial and error because not many local stores like ACE carry alot of metric threading.
OR just find a bolt same thread size/pitch of the sensor,screw it in and seal it up with some silicone or hondabond and get the radiator adapter like I have.this would be the easiest fast fix..
