some things to consider ...
keep the arrow mass weight in the 10ggp or higher range, for best transfer of limb energy to the arrow.
bare shaft all arrows. if your shooting form is reasonably consistent, they should all be flying "straight as an arrow" at 10-20 yards, with no up/down or left/right wiggles. don't be concerned about arrow grouping, look at arrow flight first and foremost.
carbons have a huge dynamic spine range, and a low static spine range - translated, this means what appears to be a "weak" static spined carbon shaft will be lots stiffer under the load of a released bowstring. with my 50-55# mild r/d longbows i'm using 29"+ beman ics 500 shafts with 350grs up front - you bet they bare shaft straight!