Coolant Temperature Sensor relocate

Just put a 98 motor in my 96. There was this one wire I just could not figure out where it went :shiver:
So, i did some reading, seems i need to relocate the sensor. Anyways, pretty sure i'm going to put it on the thermostat housing on the "flat spot".
Any idea what size pipe tap (i'm assuming its pipe thread) and drill bit i will need?

:worship:

Here is a high flow housing and it is already tapped for the extra hole.
http://www.hesco.us/shop.asp?action=details&inventoryID=133254&catId=7882