I made some for a 150# compound crossbow......from 3/8" dia. ash and a few from 3/8" dia. white oak and hornbeam. Ya need to know if it was made for "knocks", a flat butt, or slightly dimpled butt. Also measure from the string at full cock to the point where the arrow clears the end of the stock + 1" tops for length. The ones I made for Larry shot really well and behaved nicely. Never did spine them but they was stiff for sure. A hardwood shaft 3/8" dia. and 19/20 inches long should have no spine issues. 2 things though, the shafts were sawed from straight grain hardwood and turned round in a doweling jig, and I find that black walnut is too "whippy" to use for this application. hope that helps ya some, just my experience.
rich