Well i wouldnt consider it a head gasket anymore after that. I had a problem similar to yours after i replaced my intake manifold. After about two or three miles down the road my car was overheating. I knew the problem in my case it was the fans. whenever i work on my car and put it back together i always have this problem. All i have to do is grab the bracket that contains the fan motors and connects the fans to the radiator and i just shake it around figure its a loose connection but it always seems to work. And another thing about the garage telling you that it would cost more to do a head gasket than just buying a new engine. After i was told that a few times i realized that it was usually inexperienced shops that didnt deal with alot of lt1s so they were just throwing prices out there. I had gm tell me that they would charge me around three thousand dollars for a new distributor and fixing an intake manifold leak. So yeah people out there will difinately try to rip you off. I wound buying the haynes manual and buying a new distributor and installing that one and fixing the intake for around five hundred dollars. Well good luck and it definately sounds like the fans are going out on yeah.

 

It would appear that your engine was merely air bound. Have you checked the fluid level in the radiator when its cold first thing in the morning?