Your challange is to make Dr. Henry Kissinger President of the United States, by the year 1985, and with a POD no earlier then 1975.
You know the joke that Kissinger went to see Billy Graham. He wanted to convert and be born again - this time in the US!ASB, he A) is not an american born citizen, this means constitutional amendment. B) a member of the nixon administration so intimately associated with it is not going to be an extremely popular person soon after C) 10 years is not enough time
Well, the OP said a POD no earlie rthan 1975, and he was in the cabinet for part of '75, not sure how long. So...
1975: During the State of the Union speech, Kissinger is out of the country on some foreign business. if he wasn't in OTL, then his needing to be out can just be be caused by the group responsible for whta's below.
A major terrorist attack - using some chemical or biological agent (so people don't automatically blame the SOviet Union and launch nukes) - kills the entire cabinet, the President, V.P, and most Congressional leaders. There is always one person held back who can assume the Presidency, but they get him, too.
Rather than have a *major* crisis, Kissinger is recalled to Washington by the remaining 20 or so Senators and 80 or so Representatives (too few to elect a new Speaker or President Pro Tem) to become Acting President. He does well enough that the public calls for him to remain, and so a Constitutional Amendment is passed allowing foreign-born residents to run for President, but greatly restricting how they do it. (i.e.: A naturalized citizen for 25 years, not domiciled outside the U.S. during that time, etc.)
Now, who that group would be, I don't know; there were massive protests during the Vietnam War, and lots of groups mad at the government, but none mad enough to do that, are there? I'm not sure.