Graham,
You are so right. Let’s not forget the other two pyramids too. Dormion's work was based on the premise of revealing a hidden chamber accessed via the queens chamber floor, however all of the details he points out IMO reveal an older structure. The elevation of all interior pavements and the off-center passage alignment point to this claim. The only pavements that do not line up are the queen’s chamber floor and the portion of the horizontal passage north to step as the course levels of the chamber continue to that point inside the passage. From the step north to the ascending passage we find that the horizontal passage agrees with the top of the pyramids 24th course level or exactly 9 royal cubits above the pyramids entrance level. From the step northward in the horizontal passage and all of the ascending passage we find the most curious passage walls. The first 40 royal cubits southward in the horizontal passage is the most peculiar; symmetrical stacking of wall stone, each stone 2 cubits in length stacked directly over another so that the vertical seams between all of them reach from floor to ceiling of the passage. In the view that the one-of-a-kind chamber niche is centered exactly double this distance, 80 royal cubits, from the ascending passage but is not centered in the chamber also has earlier structure merits. The horizontal passage has three different types of wall construction that vary significantly but are mirrored on both sides, this characteristic lends itself to three different evolutions, the last being that of Khufu's super structure.
Dormion also points out that the ascending passage has no symmetrical style in its wall constructions, but more importantly that the girdle stones at the base of the passage were actually blocking stones cut through, blocking stones based on the principle used in Sneferu's Bent, an older closing system? The pyramids entrance level corresponds to the thickness of the 18th course, hence its floor begins at the top of the 17th course (668 inches above outside pavement), add 9 royal cubits to this and you get the floor level of the horizontal passage down (southward) to the step (top of the 24th course), add 41 royal cubits to this and you have the floor level of the great step-antechamber-and kings chamber (top of the 50th course). Hence the Kings chamber pavement and all the parts of that level are 50 royal cubits above the pyramids entrance level. In all cases, outside of the queen’s chamber and the southern end of the horizontal passage (from the step south), the interior pavements correspond to the pyramids core masonry course levels.
Incorporating an older structure, for what ever reason, would also determine the north-south alignment of the passages; If the queens chamber did belong to an older structure or early phase pre-Khufu the passage alignment going to it already existed, and as we know there are significant variants found on the walls of the horizontal passage that reveal three separate approaches to its construction that occur at the step, from the step to the symmetrical stacking and all of the symmetrical stacking. Rather than build the passage like the descending (same style for its length) for some reason they chose or were forced otherwise.
As for the other two pyramids, they each have a blocked entrance passages that IMHO belonged to older structures, the alignment of these blocked passages because they belonged to pre-existing structures and chambers inside determined the north-south alignment of the new passages built for the new structure being built over the old.
Best Regards,
B.A. Hokom