Depends on what type of voice and body you have. Would you be more likely to be cast as a Writer type who is whiny, unsatisfied with the choice he made to write in Hollywood, and plays around?
Or would you be more likely to be cast as the Film Noir type of detective that Stone is? A kinda smarmy, smug detective who's always on the border between doing right and doing wrong?
If you are the type that could be cast as either character, listen to the songs from the cast album, and read the text from the City of Angels book. Discover who you identify with, or which character you enjoy more.
Then go for both anyway and hope you get the job! :)
"My dreams, watching me said, one to the other...this life has let us down."