Gatech; How did your cooling system look before you drained and filled? Was it very rusty? Not that it matters much, now, but I'm thinking of the water pump impeller as Sidom had mentioned. If the system was very rusty, it is possible that the impeller has rusted away enough to affect flow. It is very rare, but I've also seen the impeller come loose from the hub. (originally, pressed on) Another thing is a plugged radiator. For the following tests, drain and save your anti-freeze so you can re-use it. Fill the radiator with water. Remove the lower radiator hose. The water should gush out. Using a garden hose, you shouldn't be able to keep up with the water flowing out of the bottom of the radiator. Another test, although may be hard to do, at normal operating temperature, feel the radiator with your hand. The temperature should be equal, throughout. If you feel a spot that is cool, then it is plugged. With the thermostat still out and the engine idling and cold, remove the upper radiator hose. Careful that you don't get a bath. It should shoot water out like a firehose. Of course, only run it for a few seconds to watch the flow from the water pump. If you didn't know, cold water from the radiator goes into the water pump, then throughout the engine, then back into the radiator through the upper radiator hose past the thermostat when it opens. So, it's normal for the lower hose to be cool and the upper hose to be hot.
Now, back to the head gasket issue. Head gaskets generally will blow into an exhaust port, rather than into the crankcase. So, pretty common to see a blown head gasket with no water in the oil. This is an easy test. Either with a chemical, available from most parts stores, or with an exhaust gas analyzer which any shop that does emission repairs, will have. That's actually where I'd start, first. Eliminating, or confirming, the head gasket.
