For everyone wondering, any player that signed a free agent contract prior to the beginning of the 2012 season can be traded beginning on December 15, 2012. This includes Green.
I love that everyone is on-board with Varejao. He'd be the best fit for this team, and would allow for KG to bounce between PF and C depending on game situations. Varejao rebounds, can score around the rim, and plays with a mean streak that we really haven't had since Perk left. Imagine how his mean streak will play against Bron Bron, who abandoned him in Cleveland. I'm thinking Varejao would love a chance to smash into Bron near the basket during the playoffs. He's also the cheapest option of the three.
Smith and Big Al are a toss up. They're both pricey, would probably cost more players to bring in, and they both have flaws in their game which would limit their use here - Smith settles for far too many long-2s, Big Al is sometimes very passive and seems a bit too nice on the court (def doesn't have Varejao's mean streak).