I'ma gonna throw this up here, You are holding a ticking time bomb.
You "new to XS650’s and motorcycles in general." And you bought a non running "bitsa" (bits a this bits a that) I'll posit the reason the seller was dumping was because he found out he couldn't just buy random bikes parts, throw them together, and go ride. Odds are he found himself boxed into several corners with no easy way out. The project sat and festered til he found YOU! Tread very carefully, even hardened mechanical veterans can really struggle trying to bring a bunch of parts together into a safe operating machine. The odds against a new to motorcycles guy, starting with someone else's mess, doing that are steep. AND you may not know all the problems until the cliff top is in your rear view mirror. We will do our best to help out but this is dangerous territory. I would suggest having an experienced hand give the bike a going over before you attempt to ride it.
Respectfully, gggGary