Many thanks to OtherEric for uploading this. Fascinating on several fronts.
Severin, of course, was doing art for the Atlas Wyatt Earp and I wonder whether his stories here were somehow unused inventory left over from Atlas. (And exactly how did Charlton acquire the rights to the Wyatt Earp title from Atlas?) But perhaps he just took Charlton scripts and drew them as he had the Atlas Earp.
I didn't spy any Maneely art in this issue (at least none that I could identify), though some of the stories struck me as rough pencils by Severin or Romita perhaps inked by Pete Morisi. But perhaps that is the Maneely art (as GCD suggests). If so, maybe it was someone else inking, as there was none of the usual Maneely sculpting linework that I tend to think of as chipping, as in a sculptor chipping away on a block of marble.
As for the stories signed by RAM, would that be Rocco Mastroserio, I guess. (At least GCD sez so.) And some of those were pretty decent art, too. All in all, a nifty scan.