i have done it a few different ways
Matts car we sourced the correct metric thread adapter that his sender fit in (paper thin bushing)
most of our cars, a 1/4" npt tap has been run into the very close metric tap on the passenger head where the plug is. (oem sensor on driver side head). no problems on 4-5 motors.
on the hot rods i am a little lazy and i pull the heater core nipples out of the water pump. holes left are perfect size to run a 3/8" npt and 1/2" npt tap. on the race cars they get brass plugs, on hot rods i put the sensor in the front one, done. not best place but lets you know abnormal temp if occurs.