Greetings,
The information on this site is well-depicted, but I'd advise caution about some of the heights shown. GM designed the rear lower control arms to be nominally parallel to the ground under a normal load/trim condition, which I confirmed to a tolerance of about 0.1". (I'm curious about the determination about the center of gravity height: how was this obtained?)
Getting the suspension pick-up point heights properly measured is very important for the G-bodies, because the upper control arm swing length is extremely short, so minor errors in height can create big errors in calculating anti-squat behavior.
This isn't a criticism of the information shown on the site, btw: the owner probably correctly measured his car. But I do suspect that the initial height of this car was higher than normal - hence my caution.
Best,
MAP