I'd like to see that line-up as soon as possible. The Sixers should use Miller, Iguodala, Young, Speights and Dalembert as their primary line-up and develop their rotation around that group. As long as they can keep Dalembert or Speights on the floor, the 2nd group should be fine.
It's a matter of Speights getting better on defense, but the best way to get him there is to give him the experience so he can learn. I think the offensive stuggles the Sixers go through could be eliminated with Speights and the others in the half court. Stopping Iguodala and Miller is difficult enough, worrying about Young and Speights coming off of picks should break most defenses.