Also, Superman fights Martian Manhunter in DC Comics Presents #27 and gets kicked around a bit before he decides to cheat with heat-vision to win.
My argument that Bronze Age Superman should be regarded as one entity, as least canon-wise, is that in spite of the awesome cosmic feats he performed in the later Bronze Age (part of the shift in storytelling technique) there was no canonical statement that he ever reclaimed the 1/3 of his power taken by the Quarrmer in Superman #242. Although there are plenty of (subjective) sources saying the depowering was ignored in practice, as a piece of canon it was never negated, and the Quarrmer's continued existence with that fraction of Superman's power was again confirmed in 1978's Superman vs. Shazam! one-shot.
Per pre-Crisis vs. post-Crisis for characters with minimal continuity alterations, I have little to contribute here, other than to remind that all existences which persevered through the Crisis were technically reformatted into the new reality, but that for some (e.g. Flash, Green Lantern) the impacts were significantly less dramatic than for others (e.g. Superman, Wonder Woman, Captain Marvel (Shazam!), to a lesser extent Batman). But regardless of how much was changed, all extant individual existences that made it through the Crisis (with the exception of Power Girl, Pariah, Harbinger, Lady Quark, Alexander Luthor, Jr., Superboy-Prime, and Superman, Lois Lane, Robin, Green Arrow, and Huntress of Earth-Two) were reformatted into retroactive natives of the new reality, just the same.