I fail to see how the solid axle would improve ride quality. I've gone through fields in both and it's much more comfortable in a IFS rig. If I were to do a SFA swap I would do what I could to use coils, probably as a four link design. Coils flex oh so much better than leafs, leafs are stiffer by design, that's why trucks still have them on the rear. I don't know about reusing the coils that came with it, you may lose height like that, but you can chop and drop the coil buckets on the frame.
As far as being worth it really depends on the person and the vehicles intended use. If you are in love with that body style and don't want to just transfer frames, then yes. The way solid axles flex is superior than IFS for the purpose of rock crawling (there's also no CV joints to grenade while articulating). If it's a sand runner, then IFS is better.
Look under the front of a Jeep or early Bronco to figure out what all you're going to be changing. Those are the best stock apps that I can think of for reference.
