I've been in contact with Randy Selby and he's going to do the conversion. I'm shipping him the rifle today or tomorrow.Bonk, I think you made the right choice in keeping the 300 H&H AHR rifle as is and converting the Ruger. Have you decided which Gunsmith to use for the conversion work? Dennis Olsen's name has come up several times on this thread. Another smith that has successfully converted 375(s) to 404 Jeffrey is Randy Selby @ https://randyscustomrifles.com/therealgunsmith/
I have a Win Mod 70 that Randy converted to a 404. It feeds like a rifle ought to and holds sub MOA groups with Von Gruff's Accuracy Load.