Take your pic. I like Curtis actions if you are going custom. He is super nice and easy to work with. Below is my 338 RUM and a present custom build which will be on a Sako M995 action. The RUM is a trued rem 700 with a 27" Bartlein barrel w tactical bolt, wyatts box, timney trigger, APA FB gen 3 break, HS percision stock, and barrel wrap. Meredith Rifles did the trigger, Wyatt box and action work and will build the next one. If you can find them the Sako M995 is a great action to build on. Tooder Meredith does great work. He will build whatever you want. At present I think he is using Defiant actions and brux barrels. I like Kreiger barrels as well. They have always served me well and been extremely accurate.
I would do a Curtis Helix or Sako M995 action with a Krieger or Bartlein barrel finished out at 27-30 inches fluted and threaded. Add a Timney Calvin Elite trigger and a Mcmillian A5 with a Wyatts box and bottom metal and it would be hard to beat. That is essentially what I am building on the Sako action in a 375/338 AI.