1968 Plymouth Barracuda

If you are considering air shocks for more rear end height, consider instead having your existing springs re-arched or add an extra leaf. If that seems like too much work, consider instead a set of load leveler shocks with the coil spring around them, they cost about the same as air shocks, but you don't have to worry about the lines or air bladders leaking down and slicing your rear tires to ribbons.
Worth about an inch or two in height. I had both on my Dusters in years past
and got tired of the air shocks leaking down. Ride quality with the air shocks wasn't that great either, the coil-over shocks rode much nicer. The best way to raise it, if you absolutely have to, is the springs, but that depends on whether you have a good spring shop nearby.
Looks like a great car, I hope I can find one that nice someday.
Alan627b