lowering park ave.

I (file://\\I) have a client that is disabled and just bought a 95 buick park ave. but needs to lower the rear of the car about 2 to 3 inches but its not only the springs it also the air suspension mods needed.He had a 92 caddy which just got wrecked which was lowered when he got it years ago, but they told him the buick is a little different, hope someone can help.