Nostalgically revisiting the comics of the 1980s since 2008.
Uh, what? That first cover is fantastic! Zeck draws Cap like nobody's business and an editor (Shooter?) goes with the reverse 3/4 of Doc Ock?
In the rejected cover, the focus is on Cap, and his reaction to Doc Ock's attack. I would have thought, by 1981, even if someone wasn't reading any Spider-Man titles, that Doctor Octopus would have been well-known enough for the tentacles and shadowed head to have been sufficient shorthand to sell the threat? Different if he were a more obscure villain, showing him properly so that readers would know who it was may have made some sort of sense then, even if it led to a less dynamic cover.