Those types of splits usually end up dictating limb width for me. They occur a lot in the osage I have used, and I look hard for them before serious wood removal from the belly. A little late for you now. I will say I have an osage with a split like that filled with good, thin ca glue that has shot more arrows than I can count, but the bow is only 40 #. If it were mine, I would see if it took some thin ca glue in, and then wrap with sinew and shoot it.