Boy howdy. I liked to thought I was never gonna get my clutch dialed in on my '81. For me, it turned out that the most important adjustment was up at the clutch lever. I wound up setting it so there was less freeplay than normal -- maybe 1/8" -- but that completely cured the problem I was having. And I was having the same problem -- the clutch not fully disengaging.
Having the adjustment set properly down on the engine case is important too, but it seems to be the adjustment that everybody expects to cure the problem, and then the lever adjustment gets overlooked.