Thanks for the parts, Guys.

[fredintoon]

The list's classifieds found me bargains in a hydraulic linear steering damper off of some kinda Suzi from DaddyG and XS650-specific damper mounting hardware from Grizld that practically defined NOS; I swear the parts were older than half the list's membership.
So here's a brief write-up on the assembly.
Bolts right on? Well yes, but first there's some stuff in the way.
Remove the top upper sidecar strut frame clamp, shorten the strut and re-install the clamp lower down.
Temporarily remove the tach cable so I can see what I'm doing.
Cut off the middle tach cable locating wire loop because it's in the way, too.
Fizz over the grinding marks.
Install the damper frame clamp after kissing out the cast half-holes with a metal cutting hole saw so it fits the frame tube nicely.
Install the steering stem plug-in arm after hacksawing and filing it's end down to clear stuff.
Serependitiously, The Suzi end screw is the same thread as the one in the arm.
All in all the installation went a lot easier and quicker than I'd expected it to.
If ever it stops raining I'll do a test drive and see what happens when I let go of the bars.
And again, thanks for the parts.

 

[txbluecollar]

Post your pics

 

[fredintoon]

sorry blue,
no pix right now, I'm between cameras.

 

[fredintoon]

Update!
The street dried up enough to let me take the rig out to to see if adding the steering damper removed the hands-off speed wobble.
Note that although the rig steered OK so long as the rider's hands were on the 'bars, the forks started to shimmy when I rode "hands off" and that phenomenon finally motivated the steering damper installation.
So I took the rig up to ~30mph and lifted my hands off the bars.
Success! Steers like a train! No shimmy at all!
Thanks again to the purveyors of obsolete parts who made it possible.

 

[grizld1]

Congrats, Fred. Glad it works for you.