Seems like they've answered you already, but you'll definitely get 60+ on ultra.
And that's without Mantle, which may give you even better performance.
Personally, Eyefinity gives me a headache, and the black bars in the middle of the screen bother me, so it's something worth looking into, but it has drawbacks, and costs quite a bit. I find it's better and cheaper to get a higher resolution, larger single monitor, they've got widescreen monitors that give you the same effect with just one screen, like
this one.