Re-arched springs will lose their strength over time and it will take a few years in a car not driven much. So, spring replacement is the best long-term solution and Bob's way of retaining part numbers is even better.
The downside with springs is they can be a lottery regarding heights and they'll never sit where you want them to be. So be prepared for some initial messing around until you get them to where you want to be. Even if you re-arched the springs, chances are is that they'll be strong and make the rear sit very high and then require re-adjusting as well - which makes them the same amount of effort as putting in new ones.