Lennox Lewis can punch and he is tall with a long reach so he will land at least one or two good punch on Larry and drop him like Renaldo Snipe did. But Larry will get up and TKO Lennox late in the fight. Larry will have to get up from a knock down to win by TKO in the 12th round.
I will pick Larry over Lennox anytime. Larry was a warrior who had boxing talent that approximated that of Muhammad Ali. In his prime, Larry was always in shape and focused which cannot always be said of Lennox who suffered defeats to or encountered difficulties against foes who he was not expected to lose or have trouble against.
A 15 round schedule would also favor Larry who I think had the better chin and longer staying power than Lennox.
Larry would have initial problems dealing with Lennox's size and longer reach but as the fight wears on, Lennox would progressively lose his energy as well as focus. Noted for his late round heroics against the then already prime and mature Ken Norton, Larry would hark back to that vintage version to stage strong, furious rallies to take control of the fight to win by close but unanimous decision.
Holmes would have out boxed Lewis and won a decision, I think Lewis would have lasted the distance, but Larry would have done enough to win a close decision.
IMO, Holmes was the far better fighter, had the better jab and held his hands up. Most couldn't or wouldn't get close enough to overtake the 6'5" Lewis. But,Holmes at 6'3" had the speed and determination to challenge Lewis and could in fight much better,IMO. Holmes by UD or late round TKO stoppage.
A prime Larry Holmes 1982, coming off of his 13th round TKO victory of previously unbeaten Gerry Cooney, vs A prime Lennox Lewis, 1998, who had just defeated Evander The Real Deal Holyfield, Who would win and why ? It would be 15 rounds.
