Tim's 68 Valiant has stock leaf springs in the stock location. He uses a set of my AR013 spring hangers to lower the car, that is it. The leaf springs are 40 years old. Off a 340 car.
Trick stuff in the rear end is the B-body 8.75 housing, adjustable anti-sway bar, DoctorDiff disc brakes, and Bilstein shocks. The leaf springs aren't the trick.