Leaf Question

I have a 3" BDS with a 2.5" AAL and 5/8" block on my XJ now. The rear leafs are not sagged and only haver 40,000 miles on them. I recently aquired a set of Rough Country 4.5" coils, Lower fixed arms and there 1.5" / 2" shackle. I was thinking of putting the shackle on my stock pack with the AAL. I will do a SYE with front shaft conversion and a set of adjustable upper arms. Will the shackle give me the right amount of lift or will it just cause the springs to flatten and not give the lift I'm looking for.

Shackle lift

Your shackle will lift half as much as it is longer than stock. If that makes any sense.
If your new shackles are 4" longer than stock they will lift 2".

I just re-read your post. Are you removing your AAL and your block and then adding the shackles?
Your stock springs with no help will sag after a while.

I will leave the AAL in, the Rough Country shackle gives either 1.5" or 2" lift. I want to get 4.5" font and rear