Guido you can use either a Heiser or Johnson. At the last Blade Show I attended....a couple of years ago I picked up two Mod. C sheaths in mint condition. They weren't cheap but the next time I find an oldie but goodie without a sheath I'll be sitting fat and happy. I found a 6" JRB this past week for the mod. 1.Tight stitch and all!
The Heiser is gonna be much more difficult but still I've seen them out there before.
Good luck fellows and......I'll see you on the beach!