Ok, so new leafs and springs assistants looks like a good start. You say you made up a couple of sets, do you have a spare one you could sell on?
I agree. I very much think the standard suspension could be significantly improved with addition of adjustable spring assists or progressive bump stops to control the peak movement. It’s not that difficult to engineer or even expensive so come on Morgan! Unfortunately the sets that I mentioned are my slow time winter project and only consist of a box of cut up metal and drawings at the moment. However you are welcome to the sketch of my originals if you need it. They may be adaptable to your car.
However that said if I had a four seater I would really want that air system!