I have ran a Bartline 3b at 24" with heavy deep spiral fluting and a suppressor. It works awesome. A #3 contour at 17.5" would be stiffer and will work great suppressed.
I would spend a few more bucks and get a Seekins PH2. the Seekins are a lot of rifle for the money and If you happen to get one that won't shoot they will take care of you unlike many of the other manufacturers.
I love seeing the Winchester M70 Elk builds. my rifle doesn't have a beautiful piece of wood on it like those, but she works pretty good at dropping bulls. 22" Kreiger barrel chambered in 416 Taylor pushing Barnes 350gr TTSX.
6mm Creedmoor or 243 are not going to really shine at long range until you get into the 105 to 115gr range. 105 bergers do great with an 8 twist and 115 DTACs need a 7.5 or faster. 87gr vmax going fast do ok but will get kicked around in the wind. 105s and heavier do much better at farther...