It appears that I may now be in the ballpark -- just have to meter, then bench test the unit.
Howabout the co-relation with the armature and the core numbers -- do they belong together in that same 12v core?
The clutch drive fits. Although I cannot confirm it's proper application 'cause there's no id on it.
If I can get some dimensions on a SDN8 clutch drive (which is appropriate for this starter core), then I can check those against this guy here.