I had a shop replace the front suspension because I had done this job myself once before on my '66 coupe, and I had no reason to do it again! While they were replacing the parts, I also had them lower the front end an inch to match the Shelby GT350 specs of the same year. This would help in the handling.
The rear suspension, I tackled myself. It took the car off the road for two months! I didn't have time but a few hours on the weekends to work on the car, so progress was slow. Siezed bolts didn't help either. On old cars, it's just an accepted thing to have bolts rusted so badly that only cutting them off will work. The front leaf-spring bolts, were the most frustrating. I ended up using a hacksaw blade with about two inches of movement to cut the hardened bolt out. The new stiffer rear leaf-springs lowered the rear an inch as well so the car sits level. It handles great!