The republican establishment today would not allow a “Reagan” to get the nomination. Has nothing to do with voters.
Yes and no. He might not get the nomination - the determining factor would be how many other Conservative candidates there were diluting the vote. This highlights the inability of Conservatives to quickly coalesce around a single candidate, allowing a GOPe candidate to get the nomination via plurality.
However there’s no way that Reagan could win a general election. Just apply current demographic numbers to the voting stats of Reagans winning coalition. There are a lot less members of the groups that voted for Reagan, and a lot MORE of the ones that voted for Carter.