No, Moore would still win. Like in the Durelle fight, Archie would find a way back into the fight and Marvin wouldn't be durable enough to recover from Archie's comeback. Would be a cracking fight, obviously.
Yes. I would take Marvin Johnson over the Archie Moore who fought Yvonne Durelle the first time. You couldn't half-ass it against Marvin Johnson and expect to win. Ever. You had to bring your A-game and, even when you did, it was usually a life and death battle. At that point, defending the light heavyweight title and fighting light heavys was an after-thought with Moore, as he was still more concerned with the heavyweights. And he was struggling against them, having just fought a draw with journeyman Howard King four months earlier. Moore was half-assing it. Johnson by clear decision or late-round TKO.
I'm quite literally the biggest Marvin fan on here with you, but this isn't true. Roy Jones half-assing would beat Marvin, as would Spinks or Foster. A prime Moore, Conn, Loughran or Ezz would also beat Marvin without putting full effort in. Among others. Hell even this version of Moore would.