It's looking like there might not have ever been more than a handful of comics published before 1976 that contained one magazine-length science fiction story -- unless we count superhero comics.
Would it be a good idea here to list any such comics that we are aware of? These would include
----the Star Trek comic books
----other TV tie-in comics -- what would those be? Time Tunnel, etc.?
----the comics version of King Kong, perhap
----other movie tie-in comics -- I seem to remember a Fantastic Voyage comic
----the Classics Illustrated magazines that adapted classics such as The War of the Worlds, Frankenstein, The Invisible Man, The Time Machine, Journey to the Center of the Earth, Off on a Comet, The First Men in the Moon, The Grasshopper Lies Heavy (just kidding!), etc. I'm not sure about all of these, by the way -- but there must be a Classics Illustrated list somewhere.
At one time I must have had the first dozen or so Star Trek comics, but I don't remember that any of them were much good.The stories were original, not adaptations of TV episodes.