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Move the arm on the brake plate a spline
Like the brake pedal and the actuating arm has a dot alignment system so does the rear brake arm and it's spindle. Have you checked these are aligned as well? If all the dots line up front and back it should work as Honda intended, if it doesn't then something is wrong. Either shoes are incorrect or brake rod is off another bike and shorter etc
So when you moved the arm on the splines did the punch marks line up? I suspected it was the spline alignment but as I said IF when they line up it still wouldn't work there was something wrong like wrong brake rod.
As Oddjob knows it used to be a common workshop "fix" to move the arm a spline when no adjustment left but still material on shoes you just had to remember to move it back when new shoes were fitted! Have you fitted new?