According to the data I got from the gun shop you make the case from a 7mm rem mag,*Case PrepAnneal neck and shoulder area. F/L size in Ackley die with expander removed. Trim and Chamfer. I.D. may need neck reaming. F/L size and fireform in chamber
I would still do the chamber cast first and as suggested and send it along to whomever you order dies from to make sure the tolerances are close. Case annealing is kind of a PITA, so get a Hornady annealing kit to make your life easier. There are a few places that will anneal your brass as well but you'll probably need a minimum of 100 pieces.
I don't get the inside neck.reaming though you shouldn't need to do that if you are starting with 7mm RM brass and it should have the same ID. Watch the shoulder as Old Roper mentioned you'll needs to be careful not to crush it. I hope you get that old treasure up and shooting soon.