Have you considered a headdress with a half mask and a mantle?  I'm suggesting a similar approach to Lion King's animals on Broadway--symbolic and suggestion more than realism.  And of course artsy. That would allow you to play up height as a suggestion of power because the headress would surely make him taller than all.  The mantle then would be removeable, and as kings wore mantles this could suggest his royalty.  I see a long fun fur used for the mantle--could be lion colored or not.  It could also extend down the top part of his arms with a loop for paws that rest on the top surface of the actor's hands (elastic loops under his palm) and include claws if needed for battle scenes or further suggestion of power.