We'll never know, but Ike looked like the real goods, KO'ing the most unhittable slick guy in Byrd and outworking the hardest puncher with the best late-rounds power and conditioning in Tua (who also had an iron jaw). Ike stood in range and took what Tua had to offer. All that said, we know Ike was a head case deep down, and Lewis was a very fine, experienced fighter who knew how to win the big fights. I see Lewis using his height, reach, speed, footwork, and power to outbox Ike to a close and competitive decision. However, given Ike's strength, condition, and power, he's not an easy fight by any means. After all, he was undefeated. We saw what Lewis did with Tua, but Ike was better than Tua. Hence, I say it is a rough, tough, close fight a la Mercer and Holyfield II, and it isn't entirely out of the question that Ike catches and stops him. Sadly, it's another great matchup we'll never get to see.
Lewis finds a home for that uppercut, he certainly wouldn’t take Ibeabuchi lightly, he wasn’t vulnerable technically, he was just vulnerable to switching off when he felt he was safe.
I don't know who would have won, but Ike certainly looked much more dangerous than Mercer 1996 or Holyfield in the rematch. That's why I think this fight wouldn't have happened anyway. Lewis would have chosen Botha or another fight with Holyfield.