"The following are their distances apart, as measured on parallels inclined – 5' to true N.— i.e., at the mean azimuth of the First and Second Pyramids; and also the distances, and the angles from these parallels, of the direct lines from one Pyramid to another:"
But this – 5' to true N.— is a rounded value of the azimuths as posted by Petrie.
The arithmetic mean of the pyramid base azimuths (with casing stones) is -4' 34.5". Therefore the N-G2-G3 azimuth is 211.856 degrees
I hope this is clear and we can agree on it.