Maybe it is just that the cooling fan isn’t coming on that is causing the overheating. When the engine overheats, is the radiator cooling fan spinning like a banshee?
The other question is why isn’t the coolant in the overflow tank being sucked back into the radiator when the engine cools? That could be caused by a radiator cap that is leaking the slight vacuum that pulls the coolant back into the radiator as the engine cools.
It might be the head gasket. But before assumng the worse, check the cooling fan and the radiator cap.