You might just about squeeze a flat bow out of it, it you bend it at the handle region maybe?
I'd mark out with two straight limbs but at an angle to each other, then narrow the handle area and try to steam bend it to line up the limbs.
If it doesn't work then you haven't wasted to much work tillering it.
Sometimes it's the challenging stave that you have nothing to lose by trying that work out the best... It also lets you try new techniques without the fear of ruining a 'good' stave.
Fortune favours the brave.
Del