Front end sag.

[62 short step]

Ok guys, you know I changed the original front suspension because it was sagging. Well I have the same problem with the 73-87 4" lift springs I put on the front. I guess it was'nt the old 61 springs its something else, I had the frame checked out on a frame machine at a local chevy dealer. They said no damage at all so what next? I swaped the front leafs from side to side same result. Talk about frustrated! I dont know where to look next. Its 1" lower on the drivers side than the passenger side. Should I get a 1" zero rate block and be done? Here is a pic. I know its hard to see in the pic, but its noticable in person.