Quentin Tarantino never has trouble putting together good casts for his films, but his Sergio Leone-style Spaghetti Western Django Unchained is turning out to be quite something. Kevin Costner is in negotiations to join a cast that is headed by Jamie Foxx, Christoph Waltz, Samuel L. Jackson and Leonardo DiCaprio . Costner is in talks to play Ace Woody , and it's a real surprise turn for an actor most associated with good guy roles. He's the sadistic trainer of the male fighting slaves who entertain the white patrons of Candyland as well as the female slaves who are forced to be prostitutes. The club and ranch are owned by Calvin Candie ( DiCaprio ) and Ace Woody is the one who pits the "mandingo" fighters against one another, and has little qualms about mistreating and even killing the slaves who don't measure up. The roles that DiCaprio and Costner will play are every bit as sadistic as the one that Waltz played in Tarantino's Inglorious Basterds, and whi