[70 3/4T beast]

I have a 1970 Chevy truck. It is not original, and I have a couple of questions regarding the suspension. Did Chevy offer a 3/4 Ton truck with a heavy duty suspension? My truck has coil springs, helper springs, AND airbags in the rear. It rides like a pogo stick with an empty bed, but does great with about 1500 lbs in it. It has been sidelined for a little while, but I'm replacing the trailing arms now and getting it back on the road. While I'm in there, I'm thinking about changing the springs in the rear. Since it sits about as high as a 4x4, and it's a 4x2, would putting standard 1/2 ton shocks in the rear a). level out the truck, and b). improve the ride. Will they even fit? Any help would be appreciated. I'd gradually like to make this more of a street truck ( a low budget, pitiful attempt of a street truc) and less of a "Beast". Idea is to lower it front and rear. None of my friends have seen a truck with suspension like this one.