Ibeabuchi is EXTREMELY overrated. He had two, count 'em TWO, victories over world-class opposition - and one of 'em was a close decision that could have gone either way. This is a "pick 'em" fight.
Well... Chagaev looked better at the early stage of his career and he might be past his prime already... but never really looked as good in the pros as in the amateurs where he was a tremendous fighter... So in the pros I'd say Ibeabuchi, but when we say 'prime', and as the prime Chagaev was great in the amatuers, he might pull it off in a virtual pro fight... under the rules of the amateurs, he schools Ibeabuchi.
Chagaev is really not as bad as people say he is. He is a quality boxer. He may have wasted a bit of time, however, comming up as a professional. He fought far too infrequently for someone coming up in the early stages of his career (as early as 1997), and may have lost some of what made him so good as an amateur.
Chagaev was hurt by the way his career was handled from its early stages, he is very tough , very strong and a great athlete, but from working with him and helping to train him in the USA i learned one thing, he can be hurt.. Ike by a KO..
I'll add some thoughts to my initial choice. Ike was able to last 12 rounds, and win, fighting an inside fight with a prime David Tua. He was also able to hold his own and track down a prime Chris Byrd. Chagaev doesn't have half the power of Tua, nor the infighting skills. And he doesn't have the slickness, mobility, or speed of Byrd. To make things even worse for Chagaev, he had an extremely close fight with Vladimir Virchis; a crude, powerful slugger who needs a stationary target to be effective. Bring Ibeabuchi into the mix who is far more dynamic, far more versatile, and far more skilled from a technical standpoint. If Chagaev fought his usual "stay at a distance and look for spots to counter" fight, Ike would be able to adjust, pressure him, and make him stand and fight. He would wear Chagaev down and stop him in the middle rounds.