Now I remember why we traded the Fastback GT for the convertible. My mother. She wanted a convertible - before her looks started to "go". I remember her bitching about parking the GT/4 speed, too. But the GT was great as a kid to lay down in the back with the seats folded down and to look out that giant piece of glass. Probably not what you want to do with your possible purchase...
Are new cars "better"? Certainly. But I do remember, very well, the visceral experience of the GT. I wouldn't ever call an early Mustang a shitty car, (not unreliable) but even then it was rough, but a "just right" rough.