It butterflies Governor Reagan away, yes, but Reagan become famous due to his 1964 Goldwater speech. It's quite possible he runs for Senate, or perhaps Governor later on.
As for Nixon, 1964 is too soon to go again. Especially because it means going toe to toe with both Rockefeller and Goldwater, and facing JFK for the second time (he may or may not live, in the ATL).
Knowing Nixon he probably runs for President again in 1968, but of course by now we've had six years of butterflies. Perhaps RFK wins the nomination, perhaps LBJ stays on, maybe Nixon loses the primaries or the general—there are a lot of options.
California is probably governed about the same, I doubt Nixon cares one whit about the state (except as a platform to seize the Presidency) so he just leaves it to his underlings.
I'm not much for indirect butterflies. I can't see how Nixon in the Governor's chair would affect things on the democratic side. But perhaps, a Nixon who is Gov might have an impact on the 1964 primary, even if he doesn't run, now, he didn't like Rockefeller, but I can see Nixon, trying to block Goldwater, because I think he disliked Goldwater more. I may well be wrong.
But if Nixon does end up in the Presidency, which again is a might for the reasons you listed, this might butterfly away a very important event in Nixon's Presidency.
In Nixon's mind, the Kennedy's not only stole 1960 from him, but also prevented his win in 1962.
If Nixon wins in 1962, he might actually be a bit less paranoid, which makes it just possible that there isn't a watergate in this timeline, again, assuming Nixon is President.
Which, in and of itself, will change the history of the modern era.