would 2.5 inches in the rear be too much?

[Cornfield creations]

Right now I have the tuff country 4" springs front and rear on my 79. As you all know they squat with the top on, the rear seat in there and a tank full of gas. I also have a heavy sub box in the rear.
My question is since I have 4" rear springs. Would the ORD 2.5 inch shackle flip be too much? Or does the 1" add-a-leaf be plenty?

I already have a new driveshaft thanks to Jesse. I also thought the 2.5 shackle flip would help out on pinion angle a bit since I could use a little bit more. But I don't want it to stick its but up in the air.

 

[djsblaze]

I'd go add a leaf. 2.5 shackle flip will make you but sit higher, unless you pull some leaves out of your spring pack before installing the shackle flip.

 

[2Dogs]

I think the 1" ZRs will be fine. Can you pick points on the body for reference to see how much it is sagging? Have you tried placing 1" then 2.5" blocks under the rear tires?