There's Arnold Hauser's theoretical work *The Sociology of Art* which contains a great deal of rumination on dialectics, sociology and psychology as well as aesthetics.
Also *Art and Society--Essays on Marxist Aesthetics* by Adolfo Sanchez Vazquez. This was put out by MR press and might be hard to find. It has a lot of fascinating pieces like "Marx and Engels on Tragedy" etc.
There's Trotsky on Literature and Trotsky on Art and Revolution anthologies put out by Pathfinder. Progress Publishers put out useful antologies on Marx/Engels on Art and Lenin on Art. Thankfully I haven't seen Stalin on Art or Enver Hoxha on Art.
Adorno and Benjamin wrote a lot about art but are by no means classical type marxists. There's a book called *Adorno's Aesthetics* by Larry Zuidenvart which I haven't read. The *Dialectics of Seeing* by Susan Buck-Morss is an interesting book on Benjamin.
Harold Rosenberg was a Marxist for awhile. His *Theory of Beauty* is interesting.
Terry Eagleton has written some interesting things. I think he is a poor theorist but a good literary critic. His books on Shakespeare are interesting.
Victor Kiernan's study of Shakespeare is excellent.
Christopher Caudwell is another good resource.
Sam Pawlett