I have talked with foresters about why one ponderosa pine tree is straight grained as an arrow and the tree next to it is a barber's pole and they have never been able to tell me. I proposed it was wind, but then they pointed out to me that the tree I was looking at grew up in a crowded forest. If one tree would be twisted by the wind all would have been twisted! Who knows.
Whatcha got there shouldn't be too bad to unscrew if you do it 8" at a time with a heat gun after it has cured. If you take it down to near bow dimensions, you can even steam sections and unscrew it enough to bind it down to a 2x4 to cure out. Just be sure to seal the back!