“the head of Syria is Damascus.” The “head,” the capital city, of Syria, was Damascus, and the king of Damascus was Rezin.
“and within 65 years Ephraim will be broken in pieces so that it will not be a people.” This phrase has been considered problematic because Israel was conquered by Assyria and the people of Israel carried out of their land in 723/722 BC, which was only 12 or 13 years after Isaiah gave this prophecy to Ahaz. However, the process of replacing the people of Israel with pagan people continued long after any initial conquest and exiling of captives to Assyria. The people who wanted to build the Temple with Ezra (Ezra 4:1-5, esp. v. 2) were brought to Israel during the reign of the Assyrian king Esarhaddon (c. 681-669), and that would have been within the 65-year period of time mentioned here in Isaiah 7:8. It is quite possible that Israel was not considered completely broken up and no longer a cohesive “people” until that time when the people of Israel would have been very settled in the places to which they were taken and the area of Samaria was so settled by pagans that even by New Testament times the people there were not integrated into the major Jewish population.