If I wanted a 270Wby, I would just build a 270WSM and eliminate expensive brass, a belted case and a longer action and still have the same ballistics. The .264 Win is a fine cartridge with a nice selection of bullets with high BC's. My pick would be the .264.
I have both the Weatherby and a WSM, the WSM is lucky to come within 200fps of the Weatherby in equal length barrels.