Plain black looks fine, but it it were me and I wanted to try pinstripes on it, I'd follow the basic pattern/style of the strips you've already got on the tank.
Too much pinstriping can look bad too, so in keeping with the "less is more", how 'bout this (I added the red dual line in case you've got the red/white line on your tank - otherwise, just do the white in the same weight as on the tank... I wouldn't make it quite so sharply cornered/angular as I sketched it, but you get the idea:

Alternatively, I'd drop the lower line so that it followed along the lower edge of the fairing just above the turn signals, back to the rear