TxGoat wrote:
I'd take both springs to a spring shop, if you're lucky enough to have one, or put new ones on.
You could probably mix and match leaves from the parts car on both sides and get it fairly level, but it might be more trouble than it's worth, and you'd still have weak springs. Measure between the axle and the rubber bumper on the frame with the full weight on the springs and the car parked on a level surface. I would also spray both springs with a lubricant, like Micromist. Old springs can get stiff with dirt and rust. Grease the front suspension, too, and look for any evidence of spring issues there. Also be sure that the U-bolts that hold the rear springs to the axle are tightened evenly and to the correct torque. How tight the U-bolts are can affect ride height. Be sure tires match.

Getting the rear springs in order will probably show the front springs to be sagged. Replacements are available. Good springs and shocks will go a long way toward restoring ride and handling.