The i7-4820K is very good, but I don't believe it will be dramatically better than the i7-4770K. I guess it's all about whether you want to wait or not. The i7-4820K is projected to be cheaper when it comes out around November. I should note that the i7-4770K is (currently) slightly cheaper at Newegg.
I have been told that the i7-4770K supports RAM up to 2300. So, you might consider getting faster RAM to match. (Your mobo does not support 2300, so get 2000 or 2200 instead.)
Your case is rather expensive. If you like it's appearance, then stick with it. However, if you aren't picky... There are LOTS of good cases for $50-$80!
Rosewill CHALLENGER Black Gaming ATX Mid Tower Computer Case
To be honest, I think twin GTX 780s is overkill. If you want something better, sooner... You could get a pair of GTX 770s. (I doubt you would notice a performance difference between 2x780s and 2x770s... but you will see a price difference of about $500!)