Remington 700 LA from a chrome moly donor rifle in 300 RUM. Then have one of these excellent smiths on here true it up for you and install a Wyatt box.
Or get a Stiller Predator LA mag bolt face, but you will have to buy BDL floorplate, follower and spring for it.
If you don't ever plan on selling the rifle, I would go the Remington action route. If there is a chance of selling it in the future, go custom action. for some reason they seem to hold their value more.
There are lots of quality actions out there, so its really what you like and do you plan on keeping it. I have a Bat HR at shawn's right now getting a barrel
put on it, it ought to be a awesome rifle when its done! can't wait..