The natural taper of the red osier makes them more tolerant of different draw weights. Also if you leave the arrows long they seem to get around the bow easier. You can find one arrow that flies well for you and match the deflection on the other shafts by sanding to weaken the spine if necessary.
Try to figure out which side is the stiffest. You can do this by placing the point end of a table and holding the shaft at about 45deg at the nock press at the center and feel the resistance. Now turn it 1/4 turn and check again and so on for all four sides. Figure out which side is stiffer and cut the nock so that stiff side of the arrow is against the bow.