I "babysat" one of those cars, a 250 if I remember correctly, for about 6 months for a friend who was moving house and had nowhere to store it. I liked the convertible top arrangement, and the solid feeling of the body (unlike many convertibles).
My only complaint was related to its gearing - it was a bit slow off the line, yet when cruising the engine was really revving - over 4000 rpm. I think nowadays there are gearsets that resolve some of that frantic engine -- have you done anything like that to yours?