Thanks. I believe I've found the method to disassemble this model padlock. There is a setscrew at the base of the hole where the shackle mates with the lock. Once that is removed, I think the keyway retainer ring can be unscrewed. I need to clean up these locks as I obtained them used and they have some rust and general gunk.
I still hope someone on this list can advise me on getting additional copies of the key for this set of locks. I would hope there might be a local vendor (I'm in the San Francisco area), but I'm open to other options.