There are couple ways to get custom dies matched to your chamber.
1. the smith orders a custom resize reamer to match the needs of the chamber and makes you a set. Plan on $275-400
2. Neil Jones, send him the reamer print, he will make a set either 7/8-14 or inline. He uses a Neck size only die first, has you fire 5 cases 2-3 times, send them back to him, and the NS die. He fits a custom FL size insert into the die with shoulder bump bushings and returns it. Cost is $175 for size die and $100 for seater. Time is 30 days.
3. Buy a redding body bump die($25) and send it to JLC Precision (Jim Carstenson) in Iowa along with 10 cases fired 2x. He will take the body bump die, custom hone it to your chamber, fit it with FL bushing top and you have a custom FL bushing size die. Cost is $70 and 2 weeks. His contact info is listed at www.6mmbr.com
under tools I believe.
I have done all three, and the JLC conversion is fast and as good as anything.