Springs are "hardened" and over time they flex enough to "work harden". As metal gets harder it is more likely to crack. Time and hard work will wear them out. Re-arching might be OK for a spring that is say, 20 years old? OK here comes the "Opinion". My thinking on springs that have changed shape is that they have been over loaded. Not just one time but lots of times. I would not trust a 60 year old spring that has deformed enough to be "droopy" to hold it's shape for very long. It might be time to replace them and put new bushings in at the same time. All new springs are available from vendors for about $300 front and $400 rear. Even a "Sunday" driver should ride and steer safely.

Steve H