When you lower the front, for every 1/2 inch that you lower it, you must remove 1/32 of an inch shim from each stack. Measure the side with the good spring before you put the drop springs in it, then after for the drop. Always measure from the fender lip to the top of the rim, and write it down.
When you jack the car to change rear tires, the rear springs will fall out unless you weld a piece of exhaust tubing to the upper spring perch. About 3 inches should be sufficient. You can also tiewrap the spring to the lower perch.