Yes, he's nuts but don't tell him that I said that!
He can use hardware from other companies that will work for the boat as the Dumas hardware is, well, junk. The choices wouls be Speedmaster, Octura or Aeromarine as these can be used for either surface or sub-suface uses.
I would use another engine besides tha Fox as it's not for marine use unless he wants to fry it right away.