One thing you should keep in mind is that when we had these cars back then they were either new or about 10-15 years old.. depending on your hayday.. those cars today are 50 years old....and so are their respective components...Those springs are most likely worn out and sagging, this is most likely why the air shocks won't lift the rear. Remember that any time you change the height, it changes the pinion angle too, which can be corrected with adjustable upper rear control arms.
The front geometry was not all that great neither. If you recall any old car chase movie, you would hear alot of squealing in the corners.
That is because the tires would lean sideways because of BAD camber.
To get the look you want....I would start with new stock rear springs and install new 1-2" DROP springs in the front. Using a Taller ball joint
on the upper A-arm will correct the camber and keep the tire more vertical in the turns. Instead of drop springs you could also install a drop spindle
which would lower the front end also. Of coarse anything you do ....you must get a front end alignment. This is the safest way to have what your looking for and have a much better handling car of yesteryear.
If you really want to spend some cash..... You could put adjustable coil over shocks on all four corners! this will allow you to set your stance
from 0-2" lower. This will also cost you around $4500 for a complete handling package.. which is very pricey.
What ever you choose.....BE SAFE!!!! Not only for you, but also for everyone else.
For what I suspect you are after.....I would start with new rear springs. Talk with companies like UMI, BMR, QA-1, HOTCHKIS...ect.
They can give you the correct spring rate for what stiffness you need.
(i have seen it)