Depends what you rank for really.....he was very average at world class but had longievity as European/ British champ. If you wieght the rankings for the former then he comes up short, if you give credit for the latter..... You have to remember outside the first few places, we're not exactly picking from the most stellar group of fighters to ever walk the planet. Every position outside the top 2 is a compromise/ judgement call
If you rank him on acomplishments relative to his era, then it would be hard to make a case for ranking anybody above him apart from Lewis and Fitz. You might be able to argue that sombody like Bugner or Bruno could have beaten him head to head.