How much do you get (on average) with your 600kh?
My observations showed that 750 kh (GPU+cpu) gives 15 mBTC/day in average. At the moment it's about 10 though, at the best day it was ~24.
So, you can expect an average of 12 mBTC/day: a bit less than that right now but spiking at the times of "scamcoin" bubbles.