Clive,
I haven't had the time until this mornng to look into this, but here is what I think is going on vis a vis the G1 and G2 points you have raised.
First off, there is what I see as a discrepancy in Perring's published numbers for G2, but I believe he gives us a way to sort it out.
His original base length finding is 707.75', meaning an original half-base of 353.875'. He gives the angle as 52* 20', an angle whose tangent is 1.2954. Multiply this by the 353.875' half base length and you get 458.4' - NOT the 454.25' Perring lists for the pyramid's original height.
However, if you divide what Perring lists as the pyramid's present height (447.5') by what he gives as the present base (345.375') you get the tangent number of 1.2954. Therefore, his 52* 20' angle must be the angle that he found for the present pyramid - and may or may not be the angle he assumed for the original pyramid. He doesn't clarify his intent on this.
However, he does give us the information that implies that the present platform atop the pyramid is 9' square. This then further implies that the line of present core - if continued to an imaginary apex - can be computed by multiplying 4.5' by 1.2954 (the tangent of 52* 20'), meaning the core apex would be another 5.83' above the platform. He gives the present platform height as 447.5', add to this the 5.83, and voila! you get the 454.3' that Perring erroneously lists for the "former" (ie, original) height.
This is surely where he made his mistake. The 454.3' should have been listed as the imaginary present apex height of the core - NOT as the height of the casing of the finished pyramid.
I do not see where Perring suggests that he measured the present height of G2 by measuring the height of each of the individual courses, and as I have shown above it appears that he calculated the present height (and not the "former" height, as he states) via use of the tangent of 52* 20'. Since, as far as I am aware, Perring does not give any hint of the width of the missing casing stones at the platform level, I see no way to compute an original pyramid height using his data - except of course if one assumes that he felt the 52* 20' angle was the original angle. As I have said, he implies this, but he does not specifically state this.
I do not have the complete diagram set published by Maragioglio and Rinaldi for G2, but in their text I find no record that they measured the height of G2 by measuring the height of all of the individual courses up to the platform. Instead, they seem to defer to Petrie's findings (Parte V, pp. 50 and 102) - although they did independently confirm Petrie's 53* 10' measurement of the slope.
Perhaps I have misunderstood your argument regarding this issue, or perhaps I am missing some crucial survey data. Please advise. But if you do, I ask that you do so straightforwardly and non-cryptically. It is solely the subject matter which I find of interest, no labyrinths or rabbit holes, please. Thanks.
Best,
Lee Cooper