temp sending unit and switch locations?

[GMC3]

I finally figured out that I need both. One is connected to the gauge and the other to the idiot light. My problem is that I have vortec heads and the outlets on the heads are different sizes than the threads on the switch and sending unit. I have an edelbrock performer vortec manifold and the rad hose runs directly over the outlet where one of the switches could go. I have 2 threaded openings in the manifold on either side of the carb that are the right size however I took the plugs out and didn't see any antifreeze in there. My question is will the sending unit and switch work properly if installed in these locations or do I have to find some alternative to thread into the head?