This is n't so much a 'who would have won' thread,as it's a foregone conclusion. It's more how easily Holmes would have won. Spinks would always be blasted out by aggressive predators like Tyson,but could give the smoother boxer types an awkward time. I could see Holmes finding Michael problematic in the first few rounds,before settling down and stopping Spinks around the ninth or tenth. ????
I think a prime Larry, and I consider 80-82 within his prime, stops Spinks late. The fight in 85 was a great accomplishment for Spinks but even then he had his hands very full. I just think prime Holmes would be able to impose his will on the fight and wear Spinks down.
Prime Holmes was a top three heavyweight in the opinions of many, and not an easy man to last the route with. He showed with Marvis that he was capable of a quick start, and it would be rational to test Michael right out of the gate, something the junior Spinks brother might not expect. These are two of the most intelligent titlists of the championship distance era. If I was Larry, I'd definitely test Michael early. Holmes stunned Shavers late in the opening round of their first fight, the very moment he came of age, and had the strength to steamroll a Neon Leon coming off the best stoppage win of his heavyweight career. The typical outcome to be expected is a late stoppage, but Holmes could also opt to use his jab as a bludgeon, like he did with Ocasio. That's a heavy weapon for Michael to take repeatedly for 15 rounds. Larry might walk right through him, and march him into the floor before the championship rounds came up.
I think stylistically Spinks still gives Holmes issues but a younger fresher Holmes probably stops Spinks. Holmes had Spinks noticeably hurt a few times in their rematch especially in the 14th round in which Spinks was out on his feet Holmes just didn't have the energy levels to finish him off. One would think if Holmes was 5 years younger in that situation he probably gets Spinks out of there. I'm going with Holmes to win by stoppage in 10-12 rounds.
Spinks could never beat peak Holmes. His speed and reflexes were solidly diminished by the time he fought Spinks and even then most people think Holmes won the rematch. Lack of speed and timing was the biggest problem he had vs Spinks. I mean, think about it. Spinks willingly gave up the first 4 or 5 rounds in the rematch as he wanted (needed?) to play it safe and wait for Holmes initial freshness to subside. This was a tired version of Holmes, and in his prime Holmes was a noted long range specialist. Young Holmes is not only going to stay fresh longer, he's going to be much more lively in those for 4-5 rounds as well. We know Spinks can't hurt Holmes, he hit him with heaps of flush power punches which had no affect. Spinks has no hope and this is coming from someone that believes Holmes to be half a level overrated H2H. Spinks is going to run away early like the rematch and then try and come into the fight after 5 or so rounds. Holmes is going to be quite fresh and waiting. For me Spinks either settles for a decision loss and keeps his risks down or presses in an attempt to win. If he presses he gets stopped anywhere between, say 7 and 13.