You have a couple of really good comments here and I think they'll be obvious to you. If you rebuild your entire front end (including steering box) and leave it at original height, etc you'll have a fine pickup. If you go with IFS, you're entering a money pit, and depending on who does the work you might make irreversible changes that make everything worse. Please remember your truck was designed carefully and thoughtfully by very intelligent people...and the entire thing (especially the frame design) was intended to work as a unit. Keep it stock, adjust caster a bit higher (to help it track straighter), get new radial tires which mimic the original width as much as possible (NOT wide ones) and keep the entire thing greased regularly. Also I'd encourage you to replace your leaf springs. Those wear out, weaken, etc and new ones will make a difference. As for disc brakes, millions upon millions of electrons have been sacrificed here discussing one v the other. Drum brakes are just fine if they're correct and kept in good nick.
