if its a "senior high-school project" and you are buying parts then simply bolting it on...i would give you an F-.
show some skill in using the lathe, a welder, some design and fabrication, and check out some engineering basics... possibly an A, even if it doesnt work properly. its a first attempt...
ie, no kits.
you can have a clutch on a fourstroke...you run a slip belt clutch, remove the starter and the centrifugal clutch, and with some luck you can just squeeze it between the cranks. (i might even give you an A+ if you made a decent clutch mechanism, or did something else unusual...)
you can rack mount, use either friction drive (useless in the wet but this is only a project, not a necessity, so thats irrelevant) or chain drive. end of high school...i was using friction drive with an over-center locking clutch thingy.
either way, you can show that you can fabricate something from scratch... but then, the education system passes anyone and everyone these days, so...just buy a kit and be lazy
leaves more time to go out and party, huh?