I would run a compression check on the motor. If you have 2 cylinders side by side that are lower than the rest of the cylinders it would indicated a blown head gasket. While the plugs are out of the cylinders check them for any condesation or moisture on the plug itself. This would also indicated a blown head gasket.
With the car cold you can pull the radiator cap off, start the car, and check to see if you get any bubbles in the cooling system. This would indicate a head gasket leak into the cooling system.
One last thing, How long does it take for the car to reach it's operating temp.? If there is anything that does not appear normal it could also point towards a bad head gasket.
What caused the car to overheat? That should also be a concern seeing as the motor has so few miles on it.
I had a 350 once with a leaking head gasket that would generate a big enough smoke screen to hide my house until the motor warmed up and sealed the leak. My neighbors hated me for that car every morning that I fired it up to head to my shop.
Let me know what you find out. [img]graemlins/shield.gif[/img]