I had a 6.5 creed and built a custom 264 win mag. The wm is pushing 140gr Berger elites at 3,217fps and shooting in the .2/.3's all day long.
With the same bullet in a prc, I'd guess you'd be lucky to get 3,000fps in the same 26" barrel.
Just depends on what your setup is going to be (detachable mag or bdl), game you'll shoot with it, are you going to reload?
If you reload, I'd look at the 6.5 SAUM as well - 3,100fps easy with same 140 gr bullets and just as accurate as either caliber.
*the good thing is, if it's custom, do whatever you want! Whether it makes sense to anyone else on the caliber choice doesn't matter!
Have fun with it and let us know what you decide!