Do you really believe Nelson Rockefeller would have beaten LBJ? And in the unlikely event Rocky had won, what difference would it have made? More importantly though, you’re old enough to remember the 1980 election. We were urged then, too, to support paler colors.
Let me be clear about the point I am making, since several of you have misunderstood. Goldwater was painted by LBJ and the media as a dangerous extremist. Some people who would have voted Republican (for Rockefeller or whomever) or who would have stayed home on election day not only voted for LBJ but also in record numbers in Congressional elections for Democrats, especially in House elections, but also in the Senate where there was a net gain of two for the Dems against many entrenched Republicans. That set the stage for the radical legislation enacted in 1965 from which we have never recovered.
As for the 1980 Republican race, Reagan was never seriously challenged by Bush or anyone else. Reagan almost snatched the nomination from Ford in 1976. (Too bad he didn't because then we would have avoided the disastrous Carter presidency.)