The point isn't that Reagan was less polished in 1976, but that the conditions were infinitely worse for the GOP than in 1980. I do not think that Reagan did any better in 1980 than any other Republican would have done. (Recession, a misery index around 20%
https://en.wikipedia.org/wiki/Misery_index_(economics), long gas lines, the continuing Iranian hostage crisis--the first anniversary of which was Election Day, as the media reminded voters!-- the Soviet invasion of Afghanistan, the grain embargo which enraged farmers--why *shouldn't* the 1980 Republican presidential candidate win by a substantial margin?)
Moreover, the Electoral College would not be in Reagan's favor in 1976. The states where he would presumably do better than Ford would be in the West and the South. But Ford won every western state except Hawaii (which there is no reason to think Reagan would have won) anyway. Winning California and Nevada by bigger margins than Ford did will do nothing for Reagan in the Electoral College. As for the South, Carter's being from the Deep South gave him substantial margins of victory there; Reagan might cut into them, but in most southern states he would be unlikely to overcome them completely. Indeed, *even in 1980* Carter not only carried Georgia but came very close to carrying a large number of other southern states--Alabama, Arkansas, Kentucky, Mississippi, North Carolina, South Carolina, Tennessee.
https://en.wikipedia.org/wiki/United_States_presidential_election,_1980
By contrast, Reagan might well lose some northeastern and midwestern states Ford narrowly carried. But even if he doesn't he is by no means guaranteed victory.