The overheat can and does lead to cam seizure. The deposits in the oil passageways are loosened during the overheat, and coagulate at the narrowest point, which happens to be in the head gasket. Just turn the cam a few revolutions and you'll feel it. Look for oil in the head pockets like I said previously. If it's dry and squeaky, you'll be yanking the head to clear the obstruction. A new timing belt will treat the symptom, not the cause.