Did anyone even use the word "Establishment" with the GOP between the 1964 convention and the Tea Party?
maybe in the 1976 primaries.
The Bushes basically were the establishment between 1980 and the Tea Party era. Politicians that paid fealty to the Bushes like Boehner were rewarded. The Tea Party era overturned that order.
Reagan had the Vast majority of the endorsements during the 1980 primaries and I believe the establishment wanted Reagan to select Ford as the VP not Bush
Reagan was seen as a sort of middle-man between the base and the establishment (with his celebrity), they wanted a strong old guard establishment pick to be his VP for a reason. That's the role Bush played.