Since it may not be a good stave for a long bow, your other option would be a stiff handled bow, and try to get those knots in the handle section. 80" is real long for a flatbow, so depending on draw length you would only need about 64-68" overall.
When you draw your profile out, do it so when you eye down what would be the back of the bow, the tips and the centre all intersect. It's easier (usually) to heat correct deflex reflex in limbs than it is to correct side to side I find. You can make your handle about 1 1/4 wide,
2-3" fades, and start with 1.5" wide limbs that taper to 1/2"(for now)
When was it cut?
With my yew I wait 3 months to split, another 5 or 6 before I rough out, than another few months before I even think about bending it