Thanks Laitch -- masterful piece of searching there. I searched barrel, lock, ignition switch, lock core and cylinder but I guess I didn't combine lock and cylinder.
Anyway, I see the wafer/tang down at the bottom of the housing recess where the lock lives -- it was covered with grime. Will try to get it out when I find the key -- it's my parts bike so finding the key will take some searching of the physical variety.