Raising the rear end
the right way to do it is to put a set of springs on the car. is the car sagging because of old worn out springs or is it at stock height and you want it a little higher?
http://www.springsnthings.com/ sell springs in stock height +1" and +2" heights...
and if all you want is 2" i'm sure air shocks would be fine.. air shocks are usually fine as long as you don't pump them up to 150psi. hell i had them on my dart for well over 10 years with no issues at all.