If, for a moment, we consider the Queen's Chamber, the quality of the floor is very poor compared to the extremely fine work of the walls. Maragioglio and Rinaldi noted levelling cuts, and noted that at a least one layer of limestone flags or blocks is probably missing - the next layer must have been to hand to make sensible cuts. This is an example of specific evidence.

In the Grand Gallery a section of the sloping floor is missing, and it seems likely that a section of the floor has been removed. The slope of the hypothetical floor in between is similar, but actually steeper than the general slope. In this regard Petrie ended up with a virtual point above the floor in assessing the intended slope of the gallery.

Petrie's offsets from the mean axis of 26 degrees 16 minutes 40 seconds includes an offset from a virtual point at the foot of the gallery ie above the actual floor level! This was a peculiar presentation of the survey data. I re-calculated the true overall mean slope as 26 degrees 21 minutes. I think Petrie's assessment of the slope is correct, albeit peculiar. Petrie thought that the deviation was obviously build error, and I agree. I have a vague recollection that there is some physical evidence that there was once a floor.

The width of the gallery is 4 royal cubits. Smyth measured 11 positions along the length of the gallery and computed a mean width of 82.42 inches.
4 royal cubits x 20.61 inches per royal cubit = 82.44 inches
I think that the intended finished width was 4 royal cubits.

There are grooves on the third overlaps where the width is pi royal cubits, and these grooves run the entire length of the gallery. Smyth failed to spot these grooves, but later commented that they are represented so close to the bottom of the laps that they must have had some symbolic meaning, as they would have been unable to support much weight - and I would add that the grooves would have been cut higher up the laps if a false ceiling was intended.

Hope this helps. If you have other ideas, I would like to know. The King's Chamber is geometric without any finishes, and I think the same applies to the Grand Gallery. I'm not sure why anybody would want to 'finish' stone walls with another material, or even another stone, but if this was done then I would argue that the symbolic dimensions were hidden underneath.

Mark