stock springs vs lift spring capacity

[75chev4x4]

Hey guys does anyone know if the lift springs from like tuff country are rated for the same capacity as the stock springs that came on our trucks. This is for a 3/4 ton mine for example is an 8400gvw but I out tuff country 2" springs on the truck? If I was to put a camper on will it have the same capacity as the stock ones did? I was almost wanting to go to the junkyard and get the big 8 leaf pack on the 3/4 tons and put that out back if not.