A lot of this has to do with training also. A lot has been learned since 1976, and Nadia today would benefit from that as well. She may fare a lot better than you think.
Maybe, but she didn't have the frame or build to complete the higher difficulty, more athletic moves of today. She was amazing in her time, but it's a different sport today. Is it possible she would do well? Sure. As well as she did? Not a chance.