You could throw it up on the AR15 dot com Equipment Exchange and see what interest it generates and if it worth your while to part with it.
Here is an upper only:
http://www.ar15.com/forums/topic.html?b=7&f=22&t=563678
Don't know much about KAC, but from what I have heard the DPMS would be a downgrade. I am no expert on guns but depending on what scope you have on their you probably can't touch that new for less than 2k.
I'd have a difficult time parting with your KAC if it were mine.