My car was a new 3.7 Roadster and the Suplex made a big difference.
Even my OH, as a passenger, was amazed at the change.
Same here. OH noticed right away the better ride and also feeling safer when cornering with the Suplex.
However I would not know what to advise as the variance in spring quality and spring rating seems to be a Morgan problem.
My friends 1993 +8 had the rear springs changed under warranty. He also had softer fronts with higher damping.
I had no problems with the various 1959 to 1976 4/4's that I owned.