Shocker. Morgan set up a car with a stiff front end and soft rear to compensate, and end up with the two ends feeling like they're from separate cars.
I wouldn't be at all surprised if
http://www.suspensionsupplies.co.uk/ produced a fix for the Plus Four, as they've already done for other 4-wheeled Morgans.
I've SSL's setup on my Aero, and it works for me, and for my regular passenger, who's glad to be rid of the rubbish ride over rough surfaces.
Will