Rear end alignment issue 1969 cuda

Can it be rolled back with some heat, or do I just live with it, shim the other side, or replace it?
Hardly any companies have the equipment to heat and roll the eyes. Then yes after heating the steel needs to be rehardened by quenching,
Eaton (Detroit Spring) can do it. May not be worth it.

If you liked how the car handled with those; with the springs off the car, you can make an estimate of the spring rate. Place something really heavy on them of known weight - like another person, and measure the amount it deflects. Have the person hold onto something or someone - they can throw you when shift your weight to step down!
That and the free arch will let you select similar springs.

Based on the Jeep Wagoneer springs we bought from Stengel, these are all Stanley Springs. But Triangle uses 78- part numbers as well.
You don't have to mail order, there may be a spring shop local to you that carries them.
Plymouth Valiant Leaf Springs - Stengel Bros Inc.
which overlap with
Plymouth Barracuda Leaf Springs - Stengel Bros Inc.

There also some specialty springs. The Super stock springs mentioned a few times earlier in the thread, and some companies like Firm Feel that have them for left - right handling builds.