Whitney Ellsworth (credited); Jack Schiff (managing); Mort Weisinger (actual).We know that Ellsworth was in Hollywood, pushing DC's properties for TV and movies, and that his involvement in the comics was presumably minimal. Schiff probably ran DC's offices at the time, and Weisinger did the Superman books. But....
Well, there are problems with even this chain of command. First, both the Weisinger titles (the Superman line) and the Schiff titles (which included Batman, Detective, World's Finest and Blackhawk, among others) dramatically changed once the name on the indicia was adjusted to reflect the "actual" editorship of those books.
This indicates to me that Ellsworth still exercised some strong control over DC even from Hollywood. Remember, this is in the days before email and when even fax machines were uncommon, so it's unlikely he could have been vetoing art.
Ah, but there's the rub. The inability to veto art implies also that art goes through, and if we look at the DC Superman art before Weisinger's name officially appears on the indicia, we can see that art tended to go through in that era, whereas it got stopped once Mort was given official credit.
For example, consider this panel from Action #231:
It's pretty clear that Weisinger began exerting more control over Superman's appearances at least as early as Action Comics #241, which featured the first appearance of the Fortress of Solitude:
However, with #250, the editorial change became official; Weisinger's name first appears in the indicia of that March, 1959 issue. That does not mean that the problems ended. Action #251 showed the small key again. But after that, things pretty much got standardized across the entire Superman line. Oh, there were still some occasional bloopers, like this oddball version of Kandor from #253:
So, my take? I accept that Weisinger edited the line well before 1958, but that he did not take anywhere near as active a role as he would starting with Action #241. After #250, he definitely made a more serious attempt to standardize the looks of characters and objects like the Fortress Key and the Bottle City.