You posted on a 5 yr old thread, and some things have changed a little. For one the 6.5 Creedmoor has become one of the most commonly sold chamberings today, but you probably know that, you have one.
You're stuck in the middle. Your 6.5 Cred and your 7mmRM will cover pretty much everything in North America you might want to hunt except maybe big bears, and your 30-06 has taken pretty much everything that walks, but it is pretty much in the middle and is overlapped by the other two.
That said, if you want to re-purpose your 30-06 I'd build it into something that is outside of the performance of the other two, it is a long action, and it will take pretty much any of the chamberings listed here.
Here is my thought if I was in your place. You have a 6.5 short action, and a 7mm Mag. Both a capable hunting rounds, but shoot lighter bullets, why not get something with some thump. If you want a hunting rifle build a 35 Whelen or a 338-06. Both are based on the 30-06 case and are proven performers on big game.
Check um out.