Ah, thats going to be a pretty beastly gaming rig once your done with it! ;-)
I think I would just recommend you get a new case, unless you are buying a 670 with a blower type fan. We dont even know if the 670 will fit in the case.http://c773974.r74.cf2.rackcdn.com/373928_908111_04_side_thumbnail.jpg
This is the only picture I could find. It does look like a normal ATX case, however your temperatures will be a bit hotter because of all the hot air that will be stuck in the case.