Feather contact with your arrow rest is a totally different issue from spine. If your bare shaft is grouping with your fletched arrows, and is impacting at more or less the same angle as your fletched arrows, that means your spine is close to okay. Changing your spine if it is okay would just add to your problems.
I'm a little puzzled by your comment that "all of the wear is from shooting cock feather out." If that's the case, then why are you shooting with the cock feather out?
If you are shooting with arrows that are properly tuned for your bow, then about all you can do is to rotate the nock until you minimize feather contact. Or maybe try a different rest, like a flipper rest. Ken Beck of Black Widow recommends trimming the feathers off one arrow down to maybe 1/8", and coating the edges with lipstick or something that will show up on your bow when you shoot it, because he feels that the only thing that will really hurt your shooting is contact by the quills or the part of the feathers right next to the quills. The outside edges just brush by or fold in, like God intended when he made feathers for us to use in arrows.
I know, I know, you don't want to wreck any more arrows. But you have to learn to refletch sometime, don't you? And now is as good a time as any to get a Bitzenburger and learn to glue them back on.