How much drop with just airbags?

[chevydog66]

I have a 72 GMC 1500 with rear leaf springs. How much drop can I get with just installing air bags? How much drop will I get from stock ride height? Currently, I have 1 coil removed from the front springs. And 2" drop shackles in the rear. I have 2 1/2" drop spindles sitting in my shed right now that I plan on installing this summer. I am also considering purchasing 3" drop leafs for the rear. I have other projects too (66 Chevelle) so I don't really want to spend $1500+ for a drop. Although, I want to be able to tow my 66 Chevelle to the track and car shows (Woodward) and (Chevellabration). Pics of both vehicles are on my signature. Thanks for the help!!