I drank the Mountain Dew when the 270WSM came out in a Win Model 70, that action restricted COAL like I have never experienced, used it for a while as is, wasn't happy so I sold it.
Moving on, I built several WSM's, 25, 6.5 & 338 on both REM 700 SA/LA and standard Win Model 70 actions. The SA was also restrictive in COAL. The REM LA was a head scratcher, feed rails required widening, feed ramps altered and notching of the action, regardless of bolt altering were all needed.
The Win Model 70 required less 'work' to feed well and you could load any length bullet with ease.
I should've started with RUM sized actions in the first place, but they were difficult to obtain here with regularity.
Cheers.