Hi Don,
Regarding your question whether the alignments of the three matching rectangles is coincidental or not, I would consider deviations greater than 1 meter in 1000 as questionable. The distance from the Northeast corner of G1 to the Southwest corner of G3 is 1165 meters. There are numerous alignments across the plateau with deviations of less than 1 meter.
In your "3 Rectangle" drawing, the white rectangle corner is positioned at the Southwest corner of G1 and the side runs near the corner of G2. The point on the side of the rectangle that should align with the corner of G2 is 16.25 meters from the corner. The corners of the two pyramids are 172.59 meters apart. Than equates to 94 meters in 1000.
Regarding spirals that fit, below is an sample of a Goldern Section Spiral that touches the South base of G1 and the Northwest corners of G2 and G3. The center of the spiral is 20.83 meters Southwest of the central intersection. Since this point is in the center of the plateau, I would consider the deviation to be 20 meters in 500, or 40 in 1000.
Regarding the grid, I'm not clear about what you want. Describe it in more detail and I'll create it for you.
C. Wayne Taylor
Richmond, Virginia USA