Not Morgan related but I really don't like Pirellis at all, had a few bad experiences with them. Goodyear F1s consistently get excellent reviews from all manner of high-powered cars, as do Michelin Pilot Super Sports.
I think it'd be worth it if you took your car to a laser alignment place when you have them changed, as they can correctly set up castor, camber, other geometry etc. rather than just doing a simple balance. Might cost a few quid but should transform the car if it's 'out'.
