R23 should be good and maybe will have a higher velocity. No experience with the 6.5x06 but it is good in the 25-06 and 270 so should do well for you. I am slowly replacing most of my R22 loads with R23.

"When you disarm the people, you commence to offend them and show that you distrust them either through cowardice or lack of confidence, and both of these opinions generate hatred." Niccolo Machiavelli