sadly the Nova Launcher icon pack does not support scaling the icons up, because the res of the source icons is too low. When going up to 135% size the icon edges get unsharp.
Sure, on a 400ppi display it is hard to see, but I see it. I guess you do not have a vector source for all the icons so you can make a real high res pack.
And I got to say, this is no real MIUI v7 style. It is more like a v6 + v7 hybrid. MIUI v7 icons have another corner rounding - v7 has more rounding, v6 icons look more square.