I do not know the answer to the chambering issue but I will tell you a few things about a 7Wby. It has freebore to ease the pressure curve. Several non-Weaterrby rifles have a lot of freebore on non-Weatherby cartridges and the most notorious of them is Ruger. There is room for a family of toad frogs to hide out for several years in there.
So if you go to a custom 7Wby chamber, it is important to decide on the freebore issue as it will affect velocity. Secondly, with a tighter custom chamber, if done properly, you can push the pressure higher before the case separates which is always an exciting event. I have probably separated 20-30 7Wby cases in my life.
With the slower burning powders available today you should be able to get 3200 fps with "soft" 160's but not the Accubond. The Accubond is a long bearing, surface hard to squeeze bullet and pressure will get bad in a hurry.
Those are my experiences and every rifle is slightly different so I do not particularly say my rifle was representative of what yours will do.
I regretted having it chambered that way. I should have gone to a 7-300Wby but I didn't know it existed until it won at Wimbledon or wherever it was.
The Smokin Fur Rifle Club