Beautiful Bronco! I had a 93. Was a bone stocker that I put a 6” Dick Cepec lift on.
With that being said, I also had a rear sag issue after the lift. Took the dick cepec blocks out and made my own. Made the slightly angled to correct the pinion pitch while at it. You could easily swap the factory blocks which look like little pizza slices from the side for slightly larger blocks and that would be super cheap. You would still have that factory ride too. You could also get some rubber springs from a company called Timbren to assist with the sag and firm up the ride a little.
Other than that, you could always buy a nice inexpensive 4” lift kit that includes all new springs if you want to have to buy some new tires and wheels.
Don’t bother re’arcing the factory springs though, it doesn’t last.
As far as coil suspension swap? I say why?
Most likely a nightmare to find the correct spring rate that works..
Definitely WAY labor intensive without any sort of real payoff. I mean unless you plan on chopping your rear end off to accommodate better departure angles when off roading, there’s no point. Leafs flex awesome, better than coils without the binding and obstruction of lower control arms, upper control arms, track bar etc..
I see no point whatsoever.