I'm almost finished restoring 1981 XS650 Special, (like you the last sticker was 1987) Its been a long journey, so don't rush the work, don't take short cuts. I soak the motor with penetrating oil (sprayed in spark plug holes) and left seat for awhile, then turned by hand, after that changed oil, replace sump filter and side oil filter, and make sure you go through ALL the wiring, unplugging electric connections clean and use dielectric grease on each. Replace the brake even if they look good, I've done a lot to this point. Make a list of what you need to do and check off what you have already done, this is just the beginning of thing I did, the guys here will add more to the list, Good Luck and BTW Welcome.