I've always preferred to use the factory thermostat housing with the cast in threaded bung. Much cleaner looking and looks factory, which it is. To use it on early intakes, a thin plate can be cut as a spacer to hold the larger thermostat in. It won't stick out far enough to interfere with the water pump/heater outlet.
This isn't the best picture, but you can see my temp probe in the thermostat housing. If you drill a small hole in the thermostat, which I think is always a good practice, the probe will get a good temp reading even if the thermostat hasn't opened yet, so you'll get a good signal for any EFI set-up.
The picture was taken before I removed my heater, so now that bung is plugged and could be used for something else.