The plate listed on the CMS fisc for the GL1200 is a 371 part number, GL1000. The 84/85 1200 clutch is the same size as the 1100. I guess Honda don't think that the difference in diameter is crucial.
I have no idea where the info came from originally. I have known it for a long time.
"Impossible Is Just a Level of Difficulty!..." If I'd wanted you to understand, I would have explained it better! (Johann Cruyff)I’d give my right arm to be ambidextrous!