Thanks for the comments.
I don't have any personal experience with the Stiller action, but they have a good reputation and I'm sure you'd be happy with it. There are a lot of good "specialty" actions on the market now; let me draw your attention to this one http://www.bighornarms.com/
Two of my shooting partners have been competing with .260's based on this action for a little over a year and we're pleased with them.
The Creedmoor has the same case head diameter as .308, so that bolt head should work fine.
I think the .260 gives you more options for brass, but the performance of the two should be a wash.