I would take soul grinders instead of skull cannons. They have access to skyfire weapons and still have the phlegm bombardment, but you dont really have the points for them unless you take off some flesh hounds and a greater reward, maybe.
But mostly you have the right idea. Only take the minimum bloodletters, and focus on:
flesh hounds
bloothirsters
daemon princes
soul grinders and skull cannons
I'd talk to khains wrath about Chaos daemons, hes a bit of an authority when it comes to that. Hes got a lot of experience and good advice. I'll send him a link to this in a
PM.