I built a custom 264WM on a trued Rem 700 action, 29” 1:8” twist switch barrel. Other barrel is in 7STW 26” 1:9.25” twist.
In the 264WM, I am running the Nosler 142g ABLR, it is an absolute tack driver in my rifles. Haven’t finished running it in yet, only had 20 down the tube but the first five shots were touching.
In my other 264WM, an EW like yours, I run 140g Accubonds through it with great results.
Best powders are RE25, H1000 and Retumbo is the bees knees.

Cheers.