Well, JFK surviving seems a good place to start...
POD is 1964. Kennedy is already dead.
I think a 1964 POD is too late for a no-Vietnam timeline. Johnson had reversed JFK's move toward disengagement within a few days of taking office in November 1963.
It's actually quite easy to avoid Vietnam. The only reason many may think its not is that, because it did happen, and the history of what led to it and all that is a part of academia, it sometimes feels inevitable. But, as this is Alternate History, we should be the best ones to understand nothing is inevitable.
One should clarify on why Johnson turned Vietnam into an American war. Johnson did fear the war would be another Korea; the problem was that he didn't feel he could get out of it, which wouldn't have been true but may have been harder for him than Kennedy. Vietnam was rather low priority; maybe 35 or so percent of Americans paid any attention to it, and of that, most felt it would either see a coalition of North and South (at least I think that was the component between these two I'm listing) or the fall of Saigon. Really, few cared about Vietnam. But Johnson, unlike Kennedy, did not have the foreign policy experience to understand it as well, or the foreign policy credentials to as easily wiggle out of it. IIRC, he also had the belief, at least for some time early on, that if you sent in enough blunt force, you could scare the Vietnamese into submission; World War 2 logic for a Guerrilla War situation.
If you want to avoid Vietnam ballooning into a US conflict, a public discussion is also something to avoid. That was seemingly Kennedy's plan; you keep information from getting to the public which may otherwise draw support for committing the US more actively in the conflict. Were Johnson of the mind to commit combat troops to Vietnam in this scenario, then a frank public discussion would be desirable to calm possible public upset.
I actually doubt any great public backlash if the US doesn't Americanize the war beyond the John Birch Society; again, very few paid attention to the war, and fewer expected Southern victory. And if Vietnam did fall to Communism, it wouldn't be any great success for the Soviets. The Communist world was fragmented; the USSR and Chinese were at odds because the Maoist felt that the De-Stalinization was wrong and the Soviets felt that the Maoists were being impractical by not being very open to diplomacy with the Western (Capitalist) world and being very gung ho about the whole global revolution idea, and the Chinese and Vietnamese had been in conflict for centuries. Indeed, in 1979 they went to war.
There also wouldn't be an abandonment of the South with the withdrawal of advisers; it'd simply revert to a policy of supply and aid, with the war viewed as theirs (the South Vietnamese) to win or lose.
So that's what you'd get in a best case scenario; the US avoids Americanizing Vietnam, reverts to a policy of aiding and supplying the South, the war is the South's to win or lose, nobody cares so no great public backlash occurs no matter what happens, thousands live, the disillusion and militarization of the US counterculture doesn't occur, and Johnson has a free hand to focus on domestic affairs and millions upon millions more in funds to commit to the Great Society.