Thanks for that extremely informative reply. You saved me from making a big mistake. Since I am not going to put in a heater for now, I was going to block off the manifold port and just run the upper and lower radiator hoses. I did not realize that the coolant needed to circulate before the thermostat opens.
Another question is: what direction does the coolant flow when the thermostat opens. Does it go into the engine from the top of the radiator, or out.