Measuring ride height

I just measure from the garage floor, to the bottom of the fender. Then match the other side.
Find the height to your taste, and your good.

PS: Before adjusting the torsion bars, loosen the 2 lower control arm nuts a couple turns.
This will stop you from tearing the bushings in the control arms. Tighten them back up after you adjust the height, and the car is on the ground.

The fenders are not necessarily the same height off the frame, so that's not a real good point to use.

As long as the frame is not sitting on the LCA bumper there is no need to loosen the nut. The LCA rotates around the torsion bar socket.