I have a setup similar to yours (65# SAII, with 2219's cut to 29") that bare shafts well. You didn't mention your point weight, but I'm using 125 grain points. You also didn't mention how far you are actually drawing the bow. Are you drawing a full 28"? I draw mine about 27 1/2", so am not getting the full 65 lbs. So if I am getting perfect arrow flight with my setup, it could be a little weak spined for you. If you are drawing to a full 28", you may be drawing 2-3 lbs more than I am.
If you can, have someone stand behind you when you shoot and see if there is a momentary blip up when you shoot feathers that is not there when you shoot bare shafts. That would indicate feather contact with the rest, which might explain your grouping. If you can't get rid of it by changing the orientation of the feathers, I would raise the nock point enough to get rid of it, because a consistent tail high is not as much of a problem as feathers hitting the rest.