I've been into sammys for years, all modified....heavily. I can honestly say, the Jeep springs on a sammy with a spring over, is definitely the way to go.
I have a lwb sammy now with fullsize jeep Grand Wagoneer springs all the way around, I love it! I did a spoa to a buddies sammy with CJ fronts in the front, and Wagoneer fronts in the back, he is absolutely dumbfounded with how well it rides and flexes.
I can guarantee you won't be disappointed.
You can use the Trailtough YJ kit, and for a nice upgrade from the YJ springs, try the 76-91 full-size Jeep Wagoneer/Grand Wagoneer(84-91)/Cherokee(76-83)/J-series 1/2 ton truck(76-88) front springs front and rear. They are 1 1/2" longer on the shackle end from the center bolt than the Yj springs. They can handle a load a lot better, flex better, move very easily, and live a lot longer than the YJs do. You have to remove a leaf from the pack, but, not a big deal, just buy the right size center bolts from a local spring place, carefully use a couple of 6" c-clamps, and make sure you take out only one or two of the shorter leaves. It is very well worth the effort!