I'd suggest you get the service manual and a set of bore micrometers and determine if the bore is in spec. If you can see cross hatching on the cylinder walls and virtually no vertical wear or glazing, you probably don't need to do much. Glazing is when that cross hatch becomes worn out of the cylinder wall and the bore gets super smooth (almost polished like). The cross hatch helps create a sort of seal as the rings move past them and that helps the compression.
My rule of thumb is to start troubleshooting with the least expensive potential solution and work your way up. Valve lap sounds like a good place to start, then see what kind of compression you have. If you are on a budget and the bore is in spec, but you have glazing, a light hone and new rings might work. If that doesn't fix things, look into rebuilding the top end...then you'll know it's fresh.
As for a title. I just jumped through the hoop with the whole "po didn't give me a title" ordeal. With a bill of sale, a surety bond, a signed affidavit that says "I swear I didn't steal this bike", and a vin and road equipment inspection, I now officially hold title and legal ownership of my xs. The worst part (for Michigan) is that I had to put enough money into the bike before I had the title to make it road worthy so it would pass inspection. It's not as much of a headache as some people will lead you to believe. I'm not sure about where you're at, but in Michigan, if the po is willing to go with you to the dmv/secretary of state, they can get an "instant" duplicate title made and sign it over to you right then and there, saving quite a bit of time and effort.
Without one it's just a pile of parts.
