I know a guy that fought Michael Moorer (and Ruddock and Witherspoon) and he said that Moorer hit un-Godly hard. Broke a few of my friend's ribs when they fought. Didn't say he was smart, though, and Spinks got all the brains for the Spinks brothers. And he could hit real hard himself, with either hand but, especially, the right.
If they fought at 175, and weighed in the same day, moorer would die after the second round. If Moorer got to re-hydrate, he'd weigh 220 and Spinks would box him, but hit him hard when he hit him. I think Spinks would win because he was the better and smarter fighter.