Around the same time period as Man-Gods From Beyond the Stars, Marvel also published a magazine devoted specifically to science fiction. Editor Roy Thomas expressed his love for many famous science fiction writers by adapting their stories into comics form. Theodore Sturgeon, Michael Moorcock, Alfred Bester, Harlan Ellison were a few of the notable names. There were articles designed to appeal to any SF fan who might be reading Analog--such as the interview with Frank Herbert in issue #3.
The cover to Unknown Worlds #6 that you see above was beautifully painted by Frank Brunner. There seemed to be a rash of crucifixation covers at Marvel during this period. Conan was nailed to a cross in Savage Sword, Warlock kind of got hammered in the Hulk. Maybe those covers really helped sales?
Unknown Worlds lasted only 7 issues (6 regular plus a special), and I have to admit, there's only one issue that sticks out in my memory. Issue #2 featured a memory story called "War Toy" by Tony Isabella and a newcomer named George Perez. It's a great yarn about a robot who serves in the military, but even better, the cover featured this character in a painting by Mike Kaluta. Kaluta was clearly inspired by that famous 1945 photograph at Iwo Jima by Joe Rosenthal. Yeah, it's cheesy, with the soldiers and War Toy raising that intergalactic America flag, but what the heck. I love it. Nuff said.
I bought a few of those Marvel SF mags, and enjoyed their stories from "very much" to "so-so", so thanks for this memory-prodder. But you didn't mention the cover artist here for #6 -- was it possibly Frank Brunner? If so, it's not his best work, but he still deserves a mention?
Regarding the "Man-Gods from the Stars" mag, I never got hold of any of those -- but I must admit that I, in the early/mid 70s was deeply suckered into the Von Danichen mythos! Sad, but true. I wised up after a few years, but while it lasted it was sure cool to think that space aliens had been on earth thousands of years ago -- and perhaps even gemetically modified apes to create Homo Sapiens!
Yes, that is Frank Brunner who did the cover to Unknown Worlds #6! In my haste, I forgot to mention that.