unscrewing plus at the end of heads

[forestb]

I have a small block 350 and I want to put the thermostat for my electric fan in the hole at the end of my head. Because I am told that that will give me the most accurate engine temperature. The problem I am having right now is that I have a thermostat for my electric fan that is supposed to turn on at 180 degrees and according to the thermostat for my gauge it is not turning on until it his around 220 degrees. The one for my gauge is in the front of my aluminum intake manifold and the one for my fan is in the rear. I have been told that the rear of the manifold is not a vary accurate place for a thermostat. My other option is a port in my intake manifold.

So I guess I have 3 questions.

1) do the ports seem like the problem?
2) what ports are the best to use?
3) If I use the port at the end of my head what kind wrench will work on the plug with the square hole? Allen wrench?