Your Quote 'I know that Petrie's measurements give 755.75 to within a whisher and have no idea where the other two measurements come from to give
Many people look at the base of the Great pyramid and say 'this has got to be 440 royal cubits I will make it fit'.and I have been guilty of doing exactly that.
It is the foot then digit and standard cubit and royal cubit furlong mile metre etc. Twenty years ago I was fooling about with volumes of pyramids and realised that the third pyramid was approximately 1/10th the volume of the Great pyramid.
I had already noticed that the length of the base of the 3rd pyramid was 1/3rd the diagonal of the Great pyramid.
356.4 imperial feet x 3 = 1,069.2 imperial and at first I said oh hang on not an even number but no it is several even numbers.
Indus feet 13.2 inches 972 feet x 16 = 15,552 digits / 25 = 622.08 royal cubits or 15,552 / 24 = 648 standard cubits and you easily see the sacred number 311.4 in these.
Roman feet 11.664 inches 1069.2ft 12,830.4inches / 11.664 = 1,100 roman feet
Greek feet 12.15 inches 12,830.4 / 12.15 = 1,056 Greek feet note 528 x 2 = 1056
I published this on the duplication of the cube using Indus measures 3rd pyramid 324 indus feet.You will recognise some of these numbers.