I did a little research recently on this very thing.  I am no expert but I concluded that you have to have special a arms to run the z400 spindles.  And the z400 hubs will not directly fit a zilla spindle so I would assume that the zilla hubs will not fit a z400 spindle.  I think the camber would be way off or something from what I remember.  I thought about having special a arms built for the z400 spindles but from what I have read there really is no reduction in the terrible bump steer that these front ends have.  And metal tech only makes them in a +2 total width.  This thing is wide enough for me.  Hopefully this helps a little...