Well, only Herring has more size than Chamberlain out of the Saints' current LB corps, so if we are talking about converting into a 3-4 and doing it with the current roster - he'd be a valid candidate for that OLB position. And in any case, he has enough size to work as an OLB, because there are other LBs around the league who have been successful at that position who were either similar or smaller in size than Chamberlain. I think it's more of a case if his skill-set fits that role, and he seemed fast, agile enough to cover receivers if need be, and a sure tackler, so based on that I'd say he could work in this new position.

Naturally, Wilson would be a clear choice to be moved back to the LB position under the conversion, but other than him, the Saints really don't have prototypical 3-4 OLB linebackers.