Here is my post from a few months ago...
I have 65~67 b-body rear with dr diff offset hangers in my AAR.....
I just went thru this exercise this past weekend with the Hotchkis springs.
the springs are close to flat (which is ideal for handling), making the bottom end of the shackles already pointing rearward and interfere with the valance panel. The valance has that clearance (just below the bumperettes), but only if the shackles aren't offset. Now that the shackle bottoms aren't centered any more in the clearance bump of the valance panel, you can't even install the valance. Also, if you bounce the rear bumper (i didn't have the shocks installed), the offset shackles bottomed and gouged right into the frame rail.
It also doesn't help the situation that the Hotchkis springs have a longer distance between the eyelets (by 1.5", unloaded, not installed). I should have taken pictures, but I was rushed to get my car off the hoist and i was mad. The springs seem way softer than stock.