Tire Wear Outside Edge

Hi Guys,
I installed new tires about 5000kms ago on my 1988 Mustang GT. The front tires are feathered pretty bad now on the outside edge (the passanger side is a little worse than the driver side). The rear tires are almost like new (the front are like new on the inside and center of the tire). I took it back to the alignment shop, but everything was within factory spec. The camber for both sides was 0.7 The mechanic recommended dropping that to 0.2 and see what would happen, but when he tried to adjust the camber down, it was already on the lowest setting. He said I may need softer or shorter springs to drop the car down a bit so he can make a camber adjustment. My car does sit higher on the front than in the rear for some reason. Maybe the wrong springs are installed or some sort of aftermarket drag launch kit. What do you guys think? Should I try new springs?

If I go back to stock springs, should I go for conventional or variable rate springs? What is the difference? Do you think this will slove my front tire wear issue?

I thought it was a toe issue as well. The front tires are only worn on the outside edge (approx 1 inch to 1.5 inches from the edge). I wouldn't say that the section of the tire is worn flat, but it has almost destoryed the thread (you can't see the groves very well on the passanger side edge). Where would I get c/c plates? Are they hard to install?

I replaced a bad ball joint and a bad bearing before I installed the tires. Maybe I will trya new set of springs and/or c/c plates. Do I need special tools to compress the springs? Can I change them meself without much trouble?