I'm guessing that with the return of Carter and Clifford we will see Vey and Pearson sent down. The only problem with that is the roster will have one too many RW and not enough LW. Even if you move Lewis to Center the roster still lacks a top 9 LW.
The guy I would really like DL to go after is Steve Ott. He would fit very well on the 3rd line, he should be relatively cheap to acquire as he is a pending UFA, he is versatile and he knows the Western Conference. The only issue I see is that he currently wears the "C" in Buffalo so maybe they don't want to trade him after already dealing Vanek?
Maybe Buffalo would be interested in Jordan Nolan to play for his dad? Maybe Nolan and a mid-round pick? I like Nolan but the Kings have too many players with similar skill sets.
King has shown he can at least keep up with Richards/Carter and Ott could always move up if he struggles. Pearson looks like he will be a good NHL player, but he's not ready yet.
Toffoli should bring the offense the top 9 needs, now it seems the Kings could really use one more guy that can play up and down the lineup and take some of the pressure off of Brown to punish the other team's defense.
Ott for Nolan and a 4th.