Tim,
Most C3 "A" arms a similar in function and design, so my experience with my 81's might help you. I removed and re-installed mine front springs last spring (that sounded weird :crazy). There is a tool that helps you compress the spring that is very handy.
To remove the spring I only used a hydraulic jack (not the handy tool) to lower the bottom "A" arm; however, to install the spring the reverse does not work as well because the lifting of the bottom "A" arm with the jack tends to raise the vehicle (specially if your motor is out of the engine bay).
The lower ball-joint has to be disconnected, and if it has not been disconnected since factory, then you gonna have to deal with the posibility of finding rivets (as oposed to nuts or bolts) that they used to secure the ball-joint to the "A" arm point.
Are you sure that it is the spring? Check all of the suspension attaching points. Also, the spring has to be positioned a certain way, or it will not give you the correct height.