In my experience, contrary to common belief, "dry" Iboga and Voacanga seeds do work. If you cut one open you will either find a colorless jelly inside, thats a viable seed, or you find nothing but dust inside, thats a dead seed. Now if you cut 10 open you can approximate your percentage or live seeds pretty close, obviously you need a bigger batch to do that.
Mind: They are desication intolerant, means you can not fully dry them, I think if you dont want them to germinate the best might be to clean them well and then keep them in an environment humid enough to slow down desication but not humid enough to propagate mold. Maybe ~70%
