Despite the absurdity of the cover scene on Superman 170 (July 1964), there is actually no need for it to be an Imaginary Story.
The issue opens with the delayed story that has Superman working for John F Kennedy on his program for improving the health of American youth. Bill Finger and Al Plastino put this story together, and it was pulled because of the president’s assassination. At the request of Johnson, the story was run in this issue, despite Kennedy having died.
Lana Lang is doing a television special on how Americans are behind Europeans when it comes to health. Apparently nothing has changed in 50 years. Kennedy gets Superman to promote health among the youth, and he does so over the next few pages.
But eating well and working out is not just for the young, and Clark Kent has to fake weakness as Perry White puts the Daily Planet staffers through their new health regime, despite the complaints of Lois Lane and Jimmy Olsen.
The health program serves Clark well when the staffers get trapped during a hike, and Clark can claim its Kennedy’s workout program that has increased his strength enough for them to escape. Supergirl cameos, along with her fan club, and Jimmy Olsen’s.
Now for the cover story, by Siegel, Swan and Klein. Luthor escapes from prison, and decides to head back in time to Krypton, woo and win Lara, and by doing so prevent Superman from coming into existence.
The plan works pretty well at the start. Luthor claims to be the hero of the planet Marlat, with some faked movies to back up his story.
He wins the trust of the Krytonians when he warns them about Brainiac coming to steal Kandor. No one believes him, until it happens. But once it has, the council are happy to listen to Luthor.
Lara is quite taken with him, despite being engaged to Jor-El. Luthor arranges for Jor-El to get trapped while on an exploration, and quickly wins over Lara.
They get to the wedding ceremony, and Jor-El is racing frantically to stop them, as if this were The Graduate. But fate intervenes, as Luthor’s anti-gravity device wears out, and he collapses under Krypton’s higher gravity. He has to admit that he is really from Earth. Once he has admitted being a liar, they brain scan him, and find out that he is from the future, and send him back to Earth.
So really, there was no need to make this an Imaginary Story, outside of making the reader think there was a possibility of Luthor’s plan succeeding.