It's called stock trim height, and known as J (Front) and K (Rear) heights.
Rather technical, but:
Front - measure 36.3" back from centerline of the front wheel to the lowest point of the rocker panel under the vehicle. Measurement is 8.62" for a T/A w/o a 4 sp, 8.66" with a 4 sp. So - about 8-1/2 ".
Rear - 16.7" forward from the centerline of the rear tire and the height is the same @ 8.5".
This basically says the car should sit flat and parallel @ the bottom of the rocker. Signbificant changes to this impact alignment. It is always better to have a little more height in the rear if anything - this is why people lower their front ends by using different front springs, and replacing the front sub frame bushings with solid 1/2" aluminum bushings. Again, jacking up a car impacts the instant center, anti squat, handling, alignment, etc. Find some old Herb Adams literature and study up.