I've done what
@Ross Wooldridge discussed (rebuilding springs) 3 times over the years.
I deviated from his suggestion, though:
I had an extra set of used springs, and borrowed a leaf from 1 set and put into the other. (I did not re-arch)
I replaced all the wear pads, center bolt, spring-pack clamps, U-bolts, etc.
I replaced all the bushings with B-body parts From Energy Suspension (or similar vendor).
Make sure to get the 2" front eye bushing, not the 1.5" used on the Hemi cars.
The shackles required knocking the pins out, re-drilling to 9/16", and using 9/16" bolts.
I got the bolts from a trailer-repair shop, and Mcmaster has suitable ones too.
You'll have some of the bushing riding on the threads of the shackle bolts, but I disassembled and inspected 1 set after 20 years of use and no ill effects.
The front bushings still look good from what can be seen.
And the beauty of the poly bushings is they are not press-fit, so can be R&R/re-lubed with minimal fuss vs the OEM.
Now - that's what I've done. It's an all-day job for sure.
Disassembling, knocking rust-layers off, reassembling and greasing, etc - just to get the springs ready to reinstall.
AND - it doesn't last as long as a new spring would.
The 20-year set I spoke of is ready to be replaced again (about 10 years overdue, actually).
The next set I do will be new, likely from St Louis Spring, and hopefully they can make me a set w/o the front eye bushing (I'll be using poly again, might even reuse the current ones!)
I have a 300L that had new springs when I bought it 16 years ago, I haven't driven it more than ~2000 miles since then, and it still sits proud and tall.
But the rubber shackles are squeaky, so they will get the poly shackle upgrade.
BTW - if you get poly bushings, make sure to use silicone grease on them.
Tip - if you have a stout breaker bar, sometimes the U-bolts are easier to tighten/snap than the effort to remove the nuts.
If you have a die grinder, cutting them a little bit makes that easier. Cut maybe 1/4-thru, on the straight section near the shackle plate.
If you cut on the top of the axle, it does not have a beneficial effect (you are then needing to bend the U-bolt, not shear the shank).