I have a build out for work right now , so I know the excitement.
As for an action I like the Howa/Vanguard for a semi custom. A Stiller Tac338 is being used on the current build.
For a barrel , Krieger is my top pick. Most barrel manufactures offer really good barrels now.
Stock options are...
I recently picked up a MBM brake off of FB Marketplace. Installed it yesterday and today took it for a spin. Vast improvement over the old brake , pistol is very controllable now. Still shoots the 115gr BT load fine , just a shift in POI.
Old Brake
MBM Brake
Todays target