As I kid, I tended to read non-superhero comcis (Richie Rich, Archie, etc), however there was a horror comic I once had that I would like to find. The cover shows a man strapped to a gurney in a dungeon. Next to him is an electronic brain under a bell jar. At the top of the stone staircase is the evil scientist who’s laughing maniacally. The victim is screaming and straining against the straps of the gurney.
Famous Monsters (or FM for short) and Fangoria used to have some really creepy cartoons back in the 70’s. So did National Lampoon back when they used to be cool. That cover doesn’t sound familiar, though. (They were all pretty lurid).
IIRC, FM (or by its full title, Famous Monsters of Filmland) was a movie magazine. You might be thinking of other Warren publications, such as Creepy, Eerie or Vampirella.
DC horror comics had some great Neal Adams covers in that era. House of Mystery, House of Secrets, The Unexpected and The Witching Hour all had lots of great Adams covers, along with some memorable cover work by Berni Wrightson and Mike Kaluta from time to time.