Yeah, if you peek under there, you'll see that both the front and rear springs are on top of the axle already. It's a suburban, not a YJ wrangler.
I ran replacement rear springs from JCW on my old 1/2 ton. Think I opted for the suburban springs, which had 5 or 6 leaves and a little more arch than the similar truck springs. They worked very nicely. On the front, there are many companies selling quality replacements. I honestly can't recommend going to lift springs if you like the way it drives stock. The lift springs are almost always way stiffer, and don't ride or flex as well unless you're running loaded. My current recommendation for the front is to find a set of factory 3 leaf springs and swap the bottom leaf into your current 2 leaf pack. (If that's what you have). That'll take the rate from about 220lb/in to 330lb/in, but that will still ride fairly well, and you'll gain about 1.5" of ride height. I had a custom pack made with 9 leaves for the front, so I could get about 2" of lift and still have a 220lb/in spring rate, which worked well on my 4500lb 1/2 ton.
BTW, the front springs were designed to have negative arch from the factory. It's not a sign of them being weak or junk, or worn out. They work fine like that. You should have about 1.5"-2" between the bumpstop and the top of the spring pad if your springs are in decent condition. A little less if you already have a 3-leaf pack up front.