No, you won't play at ultra with either: http://techreport.com/review/24703/amd-radeon-hd-7990-graphics-card-reviewed/5
With not even using everything at ultra, a single 7970 is getting 21 FPS, though it is at 1440p, so it'll be a little better at 1080p, but still not great.
I'd opt for #2. The 2nd one allows you to OC your CPU. The CPU is likely going to be something you keep longer than your graphics card, so you might as well have the strongest option there, and the 7870 XT is the same core as the 7950, with a few less shaders.