I shoot mostly hill cane or sourwood shoot arrows. Both are naturally tapered and both make excellent arrows. The natural taper plus the extra length I use(29" for 26" draw) allows me to shoot these arrows in bows from 45# to 60#. They are all heavy(600gr to 700+gr) but fly very well from my bows. I use a spine tester to find the stiff side of the shaft but don't try to match spine weight. Some of my arrows have almost 100gr difference but at 15 yards or less I don't see much difference. I don't try to shoot groups but try to place each arrow, one at a time, in the kill zone while target shooting.
The people that bought Rouge River Archery in Oregon may still make their tapered cedar shafts. You might try a google search for them.