Since someone mentioned him as VP in '68, any chance of him in '60? Say Lodge gets hit by a car and injured, and Nixon wants to go with a Congressman to seem closer to the people, and Michigan is an important state.
So, Nixon is assassinated in '63 by someone, doens't have to be Oswald. Nixon was a supporter of Civil Rights and Ford gets that done, but he opposes the Gulf of Tonkin and all that stuff, pulling US advisors out of Vietnam becasue he's concerned about the budget needing balanced. In a forced compromise with the Democrats, whose Lyndon Johnson loses election to him but is very powerful in a *very* heavily Democratic Congress, Ford grudgingly works together some sort of program to help the poor, though perhaps not as big as Medicare. He and LBJ share the glory for this, and it's more Johnson's doing, but Johnson is seen as really vaina nd sort of power hungry by some, so Ford winds up getting credit for the good things about welfare but Johnson gets the blame for the bad parts. (Hey, it's hard to get him into the top 5 but this *is* a good way for the average citizen to do so.
he leaves office in 1968 knowing that the GOP is a lock to lose big after 16 years, just like in 1912, but in 1970 he returns to Congress a la John Quincy Adams. His continued work in Congress reminds people of the good days of his administration; and when the first moon launch happens, he's right there promoting the fact that much of the space program's growth happened during his years in office, much to the annoyance of Johnson, who pushed the ideas but used up so much political capital he got squeezed out for the Democratic nomination in '68 by the eventual winner.
So, Ford remains in Congress through the 1970s, and as a former President in the public eye, and also the GOP's leading statesman, whenever thigns go badly for Democrats in the 12 years they hold office, Ford is there to champion the GOp cause and therefore make people think of how great his Presidency was.
In fact, he only served 5.5 years, so there are some calls for him to pull a Cleveland and be nominated in 1980. With the economy in a normal downward cycle, he reluctantly agrees, as there really isn't a leader (Reagan never enters the discussion) and he is asked by younger leaders to run, and he does, choosing as his running mate a young moderate named Howard Baker who then wins 2 terms in 1984 and 1988.
So, here it's not as much about what he does - though he does preside over Civil Rights, desgregation, and a bunch of other nice thigns, including a nice, robust economy - as the public perception. he's the "nice guy among the politicians," the one everyone has fond memories of who might never have risen to prominence without Nixon's death but who became a real man of the people. (In fact, 1980 wouldn't *have* to be included, but it helps.)
Maybe not top 3, and you might have people who have trouble figuring out why he's more than just above average to near-great, but, boy, he seemed so nice, and this is really just about perception and comparison, anyway.