Finally got the center stand on. As mrtwowheel postulated, the aftermarket exhaust interfered with the stand bolts, but I managed to make it work.
Not entirely easy to see, but the exhaust sits right against the stand bracket.
So I loosened up the exhaust and managed to get the stand bolted on. Took a bit of fiddling to get all the exhaust bolts back in, but I managed it. I wonder if the OP had taken the stand off to install the exhaust and then just didn't want to mess with trying to get it back on. It wasn't really all that hard. Or maybe he just didn't see the value in a center stand.
And here's the bike, sitting on the center stand. I put plenty of grease on the bolts. The spring was the hardest part. Thanks to Spockwerks for the suggestion of putting quarters in the spring to space it out, and to my big, strong son for providing the hand power.
Once I got that done, it was time for the spark plugs. 5Twins was right, the old ones were B8ES.
I replacee them with BP7ES, gapped at 0.28"
Tomorrow, it's on to the sump filter and bleeding the front master cylinder. Thanks so much to all my new friends at XS650.com. You've been way more than helpful.