In talking with the head of sales at Dakota/Nesika, he told me that Hornady has contracted to build their 300 Datoka cases from now on. I do not know if those cases have arrived yet but they will be switching over to them as soon as they arrive.
Remember on the Dakota case that the rim diameter is significantly larger then a standard belted magnum rim diameter. You will want to consider if you want to open the bolt face up on the Sako and dedicate it to that case head.
Reguarding the 7mm Wby Magnum. When it and the 7mm Rem Mag are loaded to the same pressure, with same throat design, there is NO difference between the two of them. In fact the 7mm Rem Mag brass will on average have a slight increase in case capacity.
I would never go with the Wby over the Rem Mag in a custom rifle
as you will not see any benefit with one over the other and its alot easier to get Rem Mag brass. Its to bad Remington and other ammo makers down load the 7mm Rem Mag as they do because its really a much more potent chambering then you would think looking at factory ballistics.