MJ:

Yours: "...In royal cubits of 20.62", the Descending Passage floor is 201.135 royal cubits long and the horizontal distance between the start of the Subterranean Passage floor and the south end of the Blind Passage is 63.92 royal cubits.
So, why 201.135 royal cubits or, alternatively, 63.92 royal cubits?..."

201.135 confirms the intended base width of G3...in case some individual(s) decided to remove the lower granite casing. Along with the passage entrance location, it adds to the "pre-design" of Giza evidence.

Best.
Clive.