I posted the Dufay reversal bleach in the other thread on Autochromes.

Work with copper bleaches for a number of purposes failed to perform properly in any of the work we did at EK. The only satisfactory bleaches were Dichromate, Permanganate, Ferricyanide, Ferric EDTA (and analog - homologues) and similar type chemistry. This was either rehal or non rehal types.

Copper and even other ferric salts failed miserably and organic bleaching agents were not much better.

Peroxide and persulfate are known and Kodak has published a formula for a rehal reversal bleach using them IIRC.