Before you get too far involved, do yourself a favor and change your thermostat. They're cheap and you could probably swap one for under $10. After that, do a good job of burping the cooling system. Get the front end up in the air as high as you can, so the radiator fill is the highest point in your cooling system. Let it come up to operating temp with the cap off and the coolant level should drop once the thermostat opens. Start adding until you can't get any more into the radiator, then start squeezing the upper hose, to work any air pockets out of the engine and to the radiator. Count on spending five or ten minutes just doing this task. Once you're confident that you've gotten all of the air out and te system is topped off, replace the cap and then report back. It could very well just be air in the system and not gaskets.