Id contact the manufacturer and ask for twist reccomendations.
Ive been to the Cutting Edge facility in PA, and the owner told me that his 300 gr 338 bullets wont properly stabilize in less than an 8 twist.
He even had doubts about his 250 gr in my 10 twist barrel, and he was right, they didn't work well.
No doubt other makers will offer like information on other cartridges.