The frames, springs, axles, wheels and tires are just some of the things that are beefed up to make a truck a C20. Changing the springs will just make your 1/2 ton ride rougher, it won't safely add any hauling capacity, sorry,
Scott

Scott Ward

2 1948 1.5-ton Loadmasters
The red one and The snow pusher
1 1950 3100
1 1955.1 Chevy 6500
1 1954 Chevy 6500 2-Ton
1 1955 1st Series COE 5700
1 1963 K20 (454)
1 1964 C10 (350)
1 1951 1.5-ton Dump Truck
1953 and a 1956 Ford F800

Raising a teenager is like trying to nail Jello to a tree!