There's no way Lee did anything other than, at most, rewrite some dialogue. You can be damn sure Kirby turned in a finished product. It's truly astonishing that anyone is left who believes the nonsense surrounding Lee. There are multiple examples of Stan himself explaining the "Marvel Method" and stating outright that Kirby, more so than any other creator, needed nothing more from Lee than a thumbs up for what Jack was planning for a story. And, as Lee also recounts, in the case of the Silver Surfer, Jack really didn't need the thumbs up either.
Like most, as a kid, I bought the fiction that Stan wrote all those comics. But anyone--to paraphrase George Carlin--past the age of reason who still believes that is ridiculous.
Lee also admits, in multiple places, that Ditko would turn in completed stories/art for Spider-Man. Nearly every artist Lee stole credit from is on record somewhere talking about--let's be more clear--the Stan Lee Method: A two minute "story conference" with writer/artists that did not need his help at all, and then changing dialogue on the completed work.
The ironic thing is that, at least by the mid-60s, Lee was really good at writing dialogue. He contributed to making those comics better. He was an asset and that should have been enough. But he wanted more money and credit than he was entitled to. A is A. And Lee was a terrible person.