BJ said when he was interviewed yesterday that he'll probably end up in the forwards in the future but he's not fit enough to be able to even think about it at this stage.
It would be hard to go from a centre to a forward. I can't think of a single position that would require less attrition. Hooker would definitely take the most physical fitness followed by the forwards and then fullback. There's no surprise why Gagai is asked to do a lot of the tough runs throughout games.
Luke Lewis is probably the biggest success and he was a lanky winger
The conversion to a forward should be starting now. Gradually ease him Into it, give him a big off season and have him ready to go for 2016. Treat him as a project. This would allow Sione to play centre and mamo as fullback for 2016 if we maintain gags.