I had Nate from SSG build a rifle in 7mmDakota for me a few years ago. It is very very accurate and a great example what custom rifles
should be. I used a Bartlein fluted barrel with a heavy sporter contour. The twist is 1-9 with the 5R rifling which was made famous by Boots Obermeyer from Obermeyer rifle barrels in Wisconsin. There are quite a few folks producing very good barrels out there and even though wait times have gotten better your challenge will be the lag time to have your smith receive the barrel. I prefer cut rifling, but that's just me. Folks who come to mind are Bartlein, Krieger, and Obermeyer for your barrel. I am sure others are also good, but I know all three of these outfits offer 5R rifling. Load information is a bit scarce. With the recent availability of Norma powders, I have started working on some loads with MRP. Initial results are very promising.
Good luck with your project, you will need lots of patience.