Well, when it comes to LeBron, I think what you have to worry about more than anything is his driving ability, his ability to get to the hoop. So as far as defending him, I think it's more important to have a solid defensive inside than it is to have a really good wing defender on him at all times.
We are going to have one of the best - if not the best - defensive front courts in the league next season with KG, Perk, and Sheed (all known as very good defensive players). So let's say Pierce and Grant Hill are all we have to cover LeBron. As long as KG, Perk, and Sheed are healthy, I'm not so worried.
Defend the basket well enough and LeBron has to shoot a lot of jumpshots. He'll make plenty of them, but it will limit him significantly. That's all we have to do to beat the Cavs.