Not very much, though, as there's only about 65mm in between the two side pieces bracing the extruder shelf. Less, if you have an ABL servo. It's going to be tight.

N.B.: I am in no way trying to nitpick or naysay clough42's design. I want to see it released so that I can use it myself. I'm sure any of these minor issues can be resolved or worked around in some way. I'll get different hotends if I have to, dammit.