Did Reagan pick Bush St as his VP or not? And eventually his successor? Even at the primaries, Bush was considered from the moderate to liberal wing of the party. I’m not going to argue further with you since it’s waste of time. Simply pointing out that if we look at the fact Reagan was capable to endorse someone who you wouldn’t endorse.
I'd bet he wasn't in the top 5 or possibly 10 of who he would have wanted. But the vetting process goes far beyond the candidates choice. Paul Weyrich explained it years ago. What VP choice really comes down to in most cases is one of whom got the most support. How many will walk away if this or that person is the running mate.
IOW while Reagan certainly had input the decision was likely done by inside party politics a compromise he had to make. Basically throughout Reagan's term there seemed to be a distance the two kept between each other. Poppy Bush basically stood against all Reagan stood for as his one term as POTUS would show.
Also he criticized Ford quite severely in 1976 but upon losing the nomination endorsed him. I would view the Romney candidacy the same way.