I decided to restore my old springs rather than purchase new ones, or switch to parabolic. I stripped each spring cluster down into individual leaves, and wire brushed them with an angle grinder to remove as much rust as possible. I then used an hydraulic press to remove the old bushes (using a suitable drift), and to re-arch each leaf to match its corresponding partner from its opposite spring. There were quite big discrepancies between opposite leaves. I also decided to add a small, arbitrary amount of extra arch to each leaf, just to give a little “life” to the tired old springs.
I assembled each spring and sandblasted the exposed areas. I then dismantled the springs again, and painted each leaf with rust converter and primer to neutralize the last bits of rust present in the grooves and pit marks. The new bushes were pressed into each main leaf using a bit of copper grease, and then each leaf received a coat (by brush) of Hammerite gloss black (smooth).
Once dry, the leaves were lightly sanded and packed back together with a small amount of copper grease between each one. The ease with which the leaves slide over one another now is vastly improved, which bodes well for how the new springs will perform once on the vehicle.