That's what I've heard as well, Pat. I'll give it a try. If it breaks, I'll switch gears.
Now I'm wishing I would have tried to leave a couple sapwood rings on there. That would have looked nice, a couple sapwood rings and the rest heartwood. It would have looked a little like a yew stave. Especially with these thin rings. Oh well. Too late now.
If the heartwood doesn't work out for selfbows, I could always flatten them and back them with hickory or hard maple.