you might be able to just find someones old spare stock topend on buy/sell.
I might know a guy actually, he just kitted his but it ran before, stock topend probably still chillin, and getting someones used complete topend probably easier and no more expensive than gambling on rings for that guy. Treats and doscycles have rebuild gasket sets, bearings and seals. Probably worthwhile, but If it were me I would, as suggested above, tryn see it run 1st. A caution, sme of those NOI's had a really crazy pedal engagement mechanism that's fucking straight awful to get back together. Anyone know how to tell from the outside?
oh and make sure you only ever fill the trans fluid with NON DETEGENT (ND), usually ND30 is easiest to find. and premix any ol 2 stroke oil 2.6oz/gal in your gas, duh.
Don't look to me like it's really missing all that much. new tires you should get anyway. For wiring etc, tear it all out and simplify. See if you can get spark before replacing the ignition stuff, likely it's just clean points and you be ok. Then any headlight and taillights can work for the most part, run the power from the stator and split it, one up front for always on headlight, one to the back for an always on taillight, and use hand signals for brake and turns. you also don't need a speedo, you're pretty much always going as fast as you can, and theyre not that accurate to begin with, so it doesn't matter if you're going 23 or 27 when you can only go 27 anyway, it's not like youre checking the speedo a lot, you're either going as fast as you can or you're not.
seat cover is tough to find. but paint, whatever. it'll start to run when gas gets on it. you could clear coat it and make some vinyl decals and make it look at least intentionally black.