The health issue can also be used, when you compare Dr. King to his eldest daughter Yolanda, who succumbed to complications related to a chronic heart condition, dying at the age of 51.
So if we could push him to this age, he will be dead in 1980.
If he doesn't go into politics I could see King doing, similar to what he did in 1964, by urged his supporters to vote against Republican Senator Barry Goldwater for president, to 1968 third party candidate, Alabama Governor and American Independent candidate, George Wallace
Maybe he is in California, during the California Democratic presidential primary, supporting his friend, Robert F. Kennedy, he is able to stop the would be assassin Sirhan Sirhan, a 24-year-old Palestinian, saving Kennedy's life and being chosen as running mate.
How would Richard Nixon go in round two against a younger Kennedy? How does Spiro Agnew debate against MLK?
Could King being alive in 1970 help, former Governor of Georgia Carl Sanders win a third term, keeping Jimmy carter away from the Governorship and away from politics