What temperature sensor do I use in new style head?

On my original 85 head it has 3 ports in the head, 2 are 3/8 NPT and one 1/8 NPT.
The 78 head on my newly built engine only has 1, 3/8 NPT port. But it also had an 1/8 NPT threaded hole around the corner between the valve cover and the manifold. I stuck a pipe plug in the 3/8 hole and the sending unit in the 1/8 hole