Yes, it's hard to find. I have looked before myself, which is one reason that Nate Silver Piece for the NYTs' 538 blog stuck out to me several weeks ago. He answered some questions I had been asking myself.
Gallup offered some additional analysis earlier last month as well. It may be found here . In it, they said about 1980...
"1980: Reagan's bid for the Republican nomination in 1976 paid off in 1979, when he emerged as the front-runner for the 1980 Republican nomination. Although George H.W. Bush came the closest to actually toppling Reagan in the early primaries, Reagan's closest competition in 1979 Gallup polls for support among Republicans nationwide came from Gerald Ford, who never formally entered the race. In January 1979, Reagan led Ford by 31% to 26%. Republicans' preferences for the two were about tied from May through July, but by August, Reagan was up, 36% to 22%, and he maintained a strong lead through the end of the year. When the 1979 trend is re-configured by substituting Ford supporters' second choice, Reagan's position looks even stronger -- he beat John Connally and Howard Baker by more than 20 points in each poll."
If you have access to a college library that has Lexis access, you can pull some of the network polls from back in the day. I was able to find several CBS polls from '79 and a few from NBC as well - all had Reagan leading pretty comfortably.
That makes sense because once the voting took place in the primaries it was very solid for Reagan. I was surprised on how bad Bush was in the polls in the Silver piece. He was barely alive. Bush was sharp and lively in the ‘80 debates though. Not like his run in ‘88 and of course ‘92.