David:

Yours: "... In your diagram, to prove your point, you give a value of 8.92 inches..."

Please note David...that is cubits...not inches.

Also...
It is the Niche I refer to...not the height of the Queen's chamber !

Notice the Niche being 183.8 inches in Petrie’s notes...see chapter 7 section 43, then compare to the G-gallery ceiling length of 1838 inches.
And now the math: the G-gallery length equals 10 lengths of the niche (1838.6/183.8 = 10.0003/1) and that relates to the calculated height of this pyramid being 31.42 times the height of the Niche (10 x pi).
Add to their other relationship...the G-gallery ceiling is 2.0 Rc wide and the Niche is 2.0 Rc deep...!

Also...please note: the Rc length I use is derived from the base width of the structure...not the King's chamber, and that length is 20.61 inches, assuming a base width of 440.00 Rc.

Remember...the King's chamber was built "after" the passages, G-gallery, QC, Niche and the rest of the interior; therefore the ruler used for the initial construction items mentioned is the one you must use for calculations.
To prove my point...check the height of the coffer...a different Rc length again.

The coffer and KC were probably pre-built off-site then raised and set in place and that would also account for the spaces between the chamber stones as noted by Petrie.

Sooooo...
It does not mean that the KC Rc of 20.63 inches was not their standard of measure, it means that a slightly smaller Rc of 20.61 inches was used by the construction crew of the Giza site.

Best.
Clive