What year of F do you have, I myself just picked up a 1975 750F, the black/red stripe wire from dimmer on mine has a plug in the main wire harness, I don't know if the three years of F have the same wire setup,mine has the box on the other side of the bike from the horn,that the wires join up in.
What are you going to do with the old switches,I am looking for the little copper/brass plate that the starter button makes contact with in the switch housing. This is the first F that I'm working on, But forty years working on Honda's I work mostly on 70--72 750's,cb900f's,cb1100f's and 75--78 Goldwings. PS I have two wires, it's brown with a red stripe and a yellow band on it male end, and a brown wire with a blue stripe female end with a cover that is half yellow. My three manuals lump the 75f to 77f for the same wire diagram and it's not the set up I have.
Head