Taking Frank's point a step further, I don't feel that we should think of these as "fixed" sounds, we should think of them as new sounds.
I disagree, Andy. I think what makes that sound so great is the difference in tonality from key to key as well as the environment in which it was recorded as much as anything else. I also think that the minor pitch changes needed to bring everything into tune will have only tiny effects on tape duration, if any at all. As I recall, the masters are more than eight seconds long anyway. The limitation in sound duration is more a function of tape frame mechanics and design than anything else.