For some general ideas, I'd look at older reloading manuals which had data for the 6.5x.300 and 7x.300 ... Sierra might be an ideal place to start.
It might be worth talking to the guys at Sierra in case they have some unpublished data available. They have helped me in that way.
Remember, whatever you do, that a custom rifle is even more a law unto itself than a factory rifle .. go carefully.
Tom
