OK, now we have some useful information. Assuming the service records check out, assuming the bike rides well (or at least the owner can do a good demo), and you have a handle on the mileage (being in Michigan, all-winter riding isn't a big option, which would lower mileage) and general treatment of the bike, I'd strongly consider the project. The scrapes are consistent with a simple tip-over. If that's all that's there, I wouldn't lose much sleep over them.
One quirk in the KRS' - at idle the engine shakes. They all do it and, by itself, it's not a problem or sign of a problem. Off idle and moving, even at low speeds, the engine should smooth out save for a very slight buzz in the high 4000 to low 5000 RPM range. Again, "they all do it".
Overall, I think you'll be amazed at the engine's good manners and patience with not shifting when you want to just ride and not spend time on gear-jamming. When you want to really twist the loud handle, hang on! Even a simple energetic overtaking pass can get you up to 80-90 without trying. Again, remember this is a bike designed to function at speed in a country where speed limits begin at 60 MPH, run to 75+, and go away altogether in places. At the same time, town speed limits are the 25 and 35 MPH we see here, and the bike does that well, too.
It'll be interesting to hear your comments on the K1200RS in comparison with your ST1300. I wouldn't be surprised if the ST1300 went away.