Hmm I don't know many good teams, but you might want to contact LDD (Level Desing Dreams) and offer the job to them. They are a professional team and you can find out more about them on their website:
http://lddreams.com/And this seems to be their e-mail:
Level_designers@lddreams.comEDIT: though LDD stands for Level Design Dreams they do much more than just levels
