Note: My tires right now are 245/60/15 in the rear.
The stack at the axle will be the same thickness with a 5 leaf, but it will ride stiffer.
I neglected to point out that I have "Mid-eye" springs,(These lower the car) you can get the same spring a bit taller with a different eye location IIRC.
You do realize that Mustangs,Falcons,Comets,Fairlanes are not built to have the upper shock mounts support the weight of the car? And that is what Air shocks do. And in the long run Mean66 will be better off fixing his car correctlly and that means the right wheels,tires, leaf springs and shocks.just put shackles on it if you just want it a little higher to get some tire clearance.
no need to replace the whole rear suspension just to raise the car a little. i also dont know why people hate air shocks so much, they work fine for most daily drivers, dont do anything for handling but they do what they are inteded to do.