I think you need input from somebody in your league. I'm only 6' and am about the size person these bikes seemed to be built for. Often shorter people are trying to get on these bikes and there are some taller ones too but they really have special problems or they learn to ride in a cramped position. There is not much you can do with out some sort of extreme modification I think.
My ex-girl friend Laurie rode an R75/5 and she was 4'6" or something. She rode in the city and had to stop most times next to a curb so she could put her foot down.