It really is rather easy to set the ride height that you don't need to go too crazy with comparing measurements. When i set my height, i just simply put a jack under the k-member and lifted both sides up at once. Then i was able to reach in and adjust the coil overs up or down depending on the height i wanted. I just dialed it in initially at 1/2" over what i wanted, and went for a quick drive and let it sit overnight. Next day, i remeasured and adjusted.
Really not that big of a deal, and measurements will vary between the cars based on the amount of actual weight sitting on the front suspension, so going by measurements of others may still require tweaking anyway.
It's also going to vary depending on the spring lb rating, and the free lenght.
--1988 Mustang LX 5.0--