Bowe by late stoppage. Too big. Too strong. Spinks will be out jabbed on the outside, and punished on the inside.
A spinks decision is not entirely out of the question, but for the most part I concur with Pedderrs that Bowe would prove too much of a proposition. Spinks was not well suited to take on big powerful heavyweights who were skilled, and most importantly ones who came to fight unlike Cooney, Tangstad and Holmes the first time around.
Bowe absolutely creams Spinks. Michael got by on a stick, move and flurry game plan over a lethargic Holmes who thought he was in with a decently soft challenge. A simple change in demeanor and style in the rematch, and we saw the result. And that was a fading Larry. Peak Bowe overwhelms Spinks from the start, outjabbing him and overpowering him in close with his strength and power. Michael would land some shots, but I'm not convinced he hit any harder at heavyweight than Holyfield, and Bowe weathered absolutely everything Evander could think of hitting him with, and proceeded to walk him down and beat him up. Spinks, more fragile and smaller, just gets squashed.
All Riddick. I don't think Spinks is ever going to put forth the energy level to try and match the Bowe activity level. He loves those breathers and this guy, like Tyson, forces him to work 3 minutes per round. If he cannot match the Bowe activity level, he will be forced to absorb punishment and I sure don't think he does that anywhere near the level Bowe can. 5 to 8 one-sided rounds where Bowe sets the pace and then the tko. This opponent is not going to cooperate like Cooney or Tangstad or old reflexes Holmes. The other factor is how Spinks deals with those Bowe fouling tactics. It would be turned into a tough physical fight and that stuff just does not play into what Mike Spinks did best. I sure don't see him reacting well to all that hitting on the break/hitting after the bell/hitting when ref separating them/low blows/rabbit punches/etc. Bowe did in his fights.
While I agree that Bowe should take this, I'm not so sure that I concur with the above statement. Spinks exerted himself plenty of times in his career to outwork quality opponents and came out on top against all of them, with the exception of Tyson, whom in all honesty, he didn't even break a sweat against. That said, Bowe is the heavy favorite and I agree with the rest of your post.
Spinks absolutely loved his breathers in there. Go watch the Davis bout and that's what he took away. forced the pace of the fight, not Spinks. Bowe is going to set the pace of the fight. Mike Spinks liked to throw 2 or 3 punches and then move away and regroup with that herky jerky footwork and upper body movement. Everyone else followed. That trick was never ever going to work against Tyson and that's why he had to stop and stand his ground. He prefers to pick and peck and then slide away and then start the same process all over again in 5 or 10 seconds. But the only guy to ever really force a 3 minute pace on him was Old Pops. Bowe was a busy fighter and threw lots of combos and a whole different kettle of fish than an old Johnson.