Helenius by (t)ko or Chambers on points. Chambers is very good fast and skillful fighter, but Helenius's power might still be too much for him. If Helenius connects then it's good night for Fast Eddie.
This would be a great match-up and would probably determine the best heavyweight not named Klitschko. Unfortunately it isn't likely to happen any time soon. Helenius is facing Liakhovich this month for minor WBA and WBO titles. Chambers is facing Tony Thompson (almost equally as good a match-up as Helenius-Chambers, honestly) in October in an IBF eliminator. They're both highly ranked but by different sanctioning bodies. It's doubtful their paths cross as they each angle towards a world title shot.
Well, seeing as this isn't signed or even plausible to happen until next year (if ever) and therefore there's no urgency in hurrying up to make a pick - I am exercising my right to wait and see how Helenius does in his sort-of step up (lateral move from shot Peter?) against Liakhovich, and how Chambers does against a seeming peer in Thompson. In late October I'll bump this with my answer. :good