Thanks Matt!
Arrow or Japanese boo has rather thin walls so a regular tapered foreshaft that one would use, say for cane or thick walled boo, just isn't strong enough IMO. But couple that taper with a pin, which is the dowel section that fits up in the shaft, makes for a strong joint.
Chuck up a 3/8" dowel in the drill and round down about an 1 1/2" to fit the hollow portion of the shaft. Then taper out to the full thickness of the dowel to fit the pre-tapered shaft. Glue with thin super glue. That's important. Thin glue will be absorbed more easily by the boo and foreshaft making for a stronger bond.
Oh, and don't forget to test 'em when you're finished;D! Art