If you are ever curious as to will the system work all together use http://pcpartpicker.com/ and that will allow you to know if your system will work. As to a GPU recommendation I am going to base my recommendations from most expensive to least
GTX 980
GTX 780
GTX 760
those are my recommendations even a GTX 970 will be amazing I have one myself and I love it! I plan on Dual SLIing it soon