Bill those aren't Super Stock springs they are the MP Mexico replacement spring. I have a place that does a good job here in Jersey for like $200 that will re-arch them. Maybe you have a local place by you. The air shock idea i did myself with my 66 till I figured out which direction I wanted to go.
Once I knew I just needed an inch in height I pulled them and had the work done. There is/was a bunch of talk over the years that the Mexico springs go away quickly.
In the 71 Bee I owned it had MP "Hemi" style springs which actually raised the car more than I wanted and had to install an inch steel lowering block.
Ron

MP description of your P/N:

"These extra heavy-duty O.E. Leaf Springs are just like the bias design production springs that were stock on 1968-72 A-Body vehicles with 340 high-performance engines, 1967-71 B-Body vehicles with 440 or 426 manual and automatic transmissions, and 1970-74 E-Body vehicles with 440 or 426 manual or automatic transmissions. Springs will fit any A-Body (1968-72), B-Body (1966-72) or E-Body (1970-74), regardless of engine size, and come with front bushings installed in assembly. B-Body: front 22", rear 36". Select right or left spring".