I wonder if the anti-dyskinetic properties of mucuna powder has something to do with the pharmacokinetics of slow L-DOPA release in the small intestine. It may be something like sinemet CR without the carbidopa. A low, more continuous release into the blood circulation may provide just the right blood level to mostly get past the liver decarboxylase and through the BBB by normal amino acid transport.
Zucc, is one of the mucuna products you mentioned a liquid extract? If so, that would tend to shoot holes in this idea, since the L-DOPA would already be dissolved and probably be rapidly absorbed in the GI tract.