I think Coco Bolo would be a nice choice with the riser as well.I do like Osage with Coco Bolo alot in a riser but not sure how that would work with Coco limbs and mostly Osage riser with the micarta I beam?Might be good?If he could put Osage and Coco bolo in the riser along with the Micarta that would be sweet.
I think black glass, then osage and Coco bolo on top would look nice for the riser overlays and tip overlays personally.
I just got my 2 piece bowbolt Griffin recently and its working out well for me.
Good luck with your bow.It will be nice whatever you decide on!