If your open to it, JES can rent a 35 Newton reamer. I had him rechamber and rebore my old 338 Win Mag Classic to 35 Newton and I couldn't be happier.
Mines got a 21" barrel as I had the BOSS lopped off as well.
Case forming is pretty easy, 375 Ruger case through a 35 Newton FL die, trim the cases and your done.
Mine runs 250's at 2840 and 225's around 2950. It's a hammer.
The real high side is mine functions like it was made for that rifle and the brass is incredibly tough.
