I've always thought that the Voyager episode "Riddles" would have made an excellent episode of Classic Trek.
I assume you mean with Spock reverting to the same kind of simple personality. Perhaps with McCoy in the Neelix role?
Though they did do something slightly similar in "All Our Yesterdays".
Yeah, perhaps Dr M'Benga in the role looking after Spock.
Be some interesting stuff with Chapel too.