I would rethink the tang and a foxface together in a 70g if it were me. It would be doable for a while but they both get big fast and your nutrients will soon get out of control.
My foxface went from 2" to "filleting size" (to quote TomR
) in a year and the amount of poop that comes out of my tang and my foxface is amazing.
So in IMO one or the other in a 70g tank
