Professor H was nice enough to step away from the wayback machine long enough fill us all in regarding one of the rejected covers for X-Men 33, and provides a color version of the cover as well:
"Gil Kane's X-Men cover ran into problems. First, several changes were made, including the positions of both hands on both Marvel Girl and Cyclops, Cyclops' eye-beams were added, and a lot of minor rendering lines were added or redrawn on the main figure's hands.
But then, the Comics Code apparently thought the main figure of "The Outcast" was too frightening. So The Outcast was replaced by The Juggernaut (who had been on Werner Roth's rejected cover in the first place). Juggernaut's hands were left unchanged from the previous version. The figures of Marvel Girl & Cyclops were replaced with Iceman and Angel, and their floating heads were replaced with the faces of Cyclops and Marvel Girl-- taken directly from Roth's cover!
(See this post "http://unpublishedxmen.blogspot.com/2013/06/x-men-33.html" for a look at Werner Roth's unused cover.)
Roy Thomas & Gil Kane would go on to collaborate on a wide variety of books, including the creation IRON FIST.
For Gil Kane's cover, for contrast, my choice of colors, first on "The Outcast" and then on the background, was designed to highlight their otherworldliness and evil, as well as reflect the manic intensity of Kane's art. I didn't even bother trying to make it similar to the published version, and I specifically wanted it to be as "wild" and "demented" as possible. I feel this manages to capture the look of the era (1967 was the "summer of love" and "psychedelia" after all) but also comes close to almost looking like a "black light" poster."
(Note that the second version is inked differently, and Cyclops is using his powers.)
(As always, you can catch Professor H in his wayback machine @ http://professorhswaybackmachine.blogspot.com/)