Imo, if the Inventory Stela is not a fake, but a copy, then that means Khufu was adding, restoring rather then building :-), and that doesn't match with current beliefs that this whole site dates to the fourth dynasty B.C. , the restorations, yes. It seems that everything that doesn't fit is regarded as fake for it can't be true that the Sphinx was already guarding this place in Khufu's days!
There's a Cayce reading that says the sphinx was laid out in channels, and in the corner facing the Gizeh may be found the wording of how this was founded. (195-14)
So time will tell, and somehow the truth will see the light of day.