I'd reuse the springs, but I'm a purist like that.
A good high density foam will give a better ride in some's opinion, so you could store the springs and opt for foam.
If reusing the springs, there isn't anything difficult involved in recovering them. The front bottom covers are secured by pulling the drawstring and bending the tabs on the seat pans over the edge. The other springs aren't really covered; they are secured to the frames by the act of installing the covers to the frames.
Keep in mind that these tasks were routinely carried out by 18-20ish year old motorpool mechanics. It ain't rocket science and barely qualifies as Upholstery work.
Clean and paint your springs, install a layer of rubberized hair covered with a thin layer of cotton or dacron batting, put your covers on and get to jeeping!