You're in good company, I don't think my bow blanks are even 100lb.
In any case, the orientation of the splice makes it not in the plane of maximal shear stress. There's nothing about the splice failing that would relieve the stress any more than the wood itself breaking.
Hilbilly, I think I read tht a dowel is only handy for preventing a splice joint from slipping apart when its glued up. As long as your splice length is decent (4" seems standard) I don't think you need a dowel. I don't see where a dowel would strengthen a jointin any way. The joint wouldn't fail by coming apart along the glue line, it'd seem to me to be more likely for the tension side to pull apart since you don't have continuous fibers at the joint.