Question

Hello Rabbi,
In Isaiah 7:8 it says: “For the head of Aram is Damascus, and the head of Damascus is Rezin; and within sixty-five years Ephraim shall be shattered from being a people”
According to the plain meaning of the verses, it seems that Isaiah is speaking to Ahaz about an event that will happen in another 65 years, but in practice the exile of Samaria took place about 12 years later.
The Sages and commentators connect the number 65 to the prophecy of Amos (“two years before the earthquake”), which was about 65 years before the exile of Samaria, and argue that Isaiah here is quoting or hinting to this known prophecy, rather than establishing a new count.
My question is:
From a biblical-contextual standpoint, are there real signs that this is a quotation/allusion to Amos’s prophecy, or is this mainly an interpretation meant to resolve the chronological problem? In other words, does the Sages’ solution arise from the text itself, or is it the result of a need to defend the reliability of the prophecy?
Thank you very much.