Rear Leaf Spring Help

New to repairing Broncos on my own, sufered through rebuilding a transmission, tie rods, ball joints,  and a slew of other fun projects. But now I am a bit confused.  I have a 6 inch pro comp stage 2 lift Kit on my 1989 Bronco.  I want to replace the rear leaf springs and get rid of the block and add a leaf. I have measured the block and add a leaf and with the factory shackle on the axle they add about 4 inches to the factory leaf springs and the Bronco sits pretty level. I am looking at the Alcan Leaf Springs  and to Keep things level  I am not sure if I should go with 4 inch or six inch leaves.  I see the BDS and skyjacker lift kits come with 4 inch leaves. I am not sure if that is because the Bronco sits naturally an inch or so higher in the back and the 4 inch levels it out. Any and all help is greatly appreciated.

Typically a lift kit lifts the front the stated amount but lifts the rear a little less so that in the end the truck sits level.