Thanks for some good ideas. It is a 1978 model.It helps to mention the year. The wiring on a mini-bike isn't going to be very complicated.
youtube videos can be useful. sample search >> KV75 wiring. One guy shows a good, clear wiring diagram in his video. I didn't watch
the whole thing, but his vid was looking pretty good on how to wire it up.
Also, the diagrams at Partzilla might be of use & sometimes NOS wire harnesses can be found on EB.
EB pics can be help in figuring out stuff.