The 6 Rem and AI thrive on top end pressure loads. When you neck down, neck turning should be considered, and I neck turn before necking down.
I saw these on gun broker, cases heads look perfect, primers round, and I would trust them:
Since the parent case is the 8x57 Mauser, you have some options. As you know, Norma is soft in the case head. Once in a great while, you will see Lapua 7x57 brass for sale, which usually comes across the border from Canada. You can get a set of form dies and start making brass from 30/06 brass, and this is a chore, I have done many. RWS is the Toughest, and Lapua 30/06 brass is almost as tough. Be aware of the fact that the European brass is much larger in the web, which can give you headaches. If you can ever find any of the NEW Lake City 06 Match brass, you will have a treasure, the stuff is incredibly tough.
The easy button is to shoot Hornady brass, skim turn the neck to uniform, de burr inside primer pocket, call it done.
Op, you could do a "Want To Buy" on New Winchester brass, and they are worth $1 each if you can find them. I have had 20 bags of Winchester on back order for 3 years, no hope in sight.