Being a tanto karambit, the only thing I see close is the spyderco karahawk, I believe that's a loclback, and get the blade reground? I believe it would be very expensive to convert, as others saud, custom parts/spring etc. I'd look into the karahawk and talk to Josh (Razir edge Knives) Aboit getting it reground to a shape you prefer. It'll be a bit shorter, but I see that as your cheapest/easiest option