I believe you'll need at the very least 850W.
If I were in your situation, however, I'd get a Corsair HX1050. It'll give you more than enough headroom for expandability, pumps, anything you might need.
Taking into account the build, I assume that spending a bit more money to get a much better PSU isn't that much of a problem (going from a PSU with 850 such as the TX850 or HX850 to a high-end HX1050).
I was just looking at the corsair HX1050. Looks like that's what I'm getting. Thank you!