Yes, some pictures would be good.
We'll need you to answer some questions in order to give you some advice.
Is your 37 Pontiac still running the stock suspension in the front? Rear?
Who gave you the reccomendations of which bags to use for your application?
Were the airbag kits a dedicated kit for your car or were they a universal install.
Are you using airbags or shockwaves?
What pressure do you need to run to get a proper ride height?
Are the bags mounted where the coil springs were originally mounted? Did you have to trim the frame to get the bags to fit, or were the bags selected to fit inside your frame.
What type of shocks are you using, and how are they mounted. (straight up and down? angled? Is the shock mounting point far out on the lower control arm and close to the wheel?)
Did you check for full suspension travel with the springs and shocks out before you installed the airbags?
Are you using the tall stock rubber bumpstops or the short poly ones that come with the airbags?
Did you check for full shock travel with the bags installed?
Is the front end stiffness more of a problem, or the rear? Or both ends of the car?
How much distance between the bumpstops and axle do you have at the proper ride height? Distance between bumpstop and lower control arm.
How do you know that the suspension is not bottoming out on the bumpstops.
It leads me to think that because you tried every pressure in the bags and the ride does not change, that there is an issue with the suspension itself, or the bag size, and how the shocks or bags are mounted.
I've installed a bunch of airbags, and the ride quality was easily changed with pressure changes, but too low of a pressure always made the car hit the bumpstops.
Alot depends on how much suspension travel you have, and the motion ratios . If you lower the car and install a too small bag so that you need a bunch of pressure to attain ride height and the ride will be stiff. I've had Air Ride Technologies specify too small an airbag for an application, and at the pressures required to attain proper ride height the ride was stiff, something to do with the physics of the compressibility of a gas.
What you heard about airbags in general being only good for trailer queens is not true, semi trucks have used airbags for many years because the ride quality was much better than springs...Look at a big moving truck, many of them use airbag suspension to protect the furniture and fragile items in their loads.
Buses use them, so do some railway cars. Guys with touring motorcycles use them as well. I made my own airbag setup for the solo seat on my rigid frame harley, and it rides great.
my signature lines...not really directed at anyone in particular..
BE different....ACT normal.
No one is completely useless..They can always be used as a bad example