If it were me going to a production manufactured rifle, I believe it would definitely be one that would shoot BH209 and Barnes 290 TMZ or T-EZ bullets. Accurately. Not trying to start a p match, but it wouldn't be a CVA, unless an Apex.
There's also some custom rifles, some in .45cal, along with the Remington Ultimate Muzzleloader. The RUMZ is starting to show some outstanding long range accuracy by more shooters. There's also the Ultimate Muzzleloader, although much more expensive, but extremely accurate at long range.