As mo said, replace the entire arms rather than rebuilding them. The uppers crack where the spring saddles mount & when you remove the screw in bushes, you'll probably strip the threads. The lowers have the ball joints welded in from memory. It's not really worth the trouble.
For lowering the front, I fitted 1" lowered GT springs from a local Mustang shop & relocated the upper arms (Shelby drop).
For the rear, I had the leaves reset for a 1.5" drop & an extra leaf was added. Approx $150 from memory. Any good local spring shop should be able to help you.
Evan.