I have a 1-8 twist 240 Wby that has made two kills beyond 1000 yards. I would be wiling to try to test it but the killing range would probably be less than 400 yards on the small eastern whitetails found in Maryland.
I cannot guarantee my ability to find a good load in the amount of time left before deer season.
Your bullet needs to withstand extreme velocity being as I can dust the 115 Bergers if the barrel is warm.
So let me know if 1-8 twist is OK.
1140 yards with 115 Berger
1006 Yards with 115 Berger