Reagan winning the election in '76 seems to be a popular discussion topic, but no one really talks about him getting the nomination in 1968, the first time he ran.
Let's say Nixon dies in '66 or '67, so Romney and Rockefeller split the moderate/liberal Republican vote, and Reagan narrowly wins the nomination. Let's say Wallace and Humphrey still run as OTL. Some things to consider:
1. In this scenario, there is no clean Republican frontrunner from the the beginning like they had in OTL in Nixon, so the convention will still be pretty nasty. Probably not equivalent to the travesty that was the Democratic Convention in '68, but something like a repeat of the convention in '64.
2. That being said, Reagan was a better campaigner and more charismatic than Goldwater, will probably have the broader support of the Republican Party if he picks the right running mate. And unlike Nixon, he didn't have a Checkers speech and there would be far less suspicion of him among the general public.
3. Hitting back on what I mentioned before, who would be a good running mate for Reagan?
4. Will their be debates? A big part of why their weren't any in OTL '68 is because Nixon didn't want to repeat the unpleasant experience he had in '60's debate. Reagan is, after all, the Great Communicator, and may want to put his acting ability to use taking on Humphrey.
Or maybe Humphrey doesn't want to debate, so Reagan does what he did with Anderson in '80 and has a two-man debate with Wallace, which will be interesting.
OR maybe there will be a three-man debate, which will be VERY interesting.
5. Who wins, realistically?
6. Now let's assume Reagan wins. How do things pan out?