I dunno, 260. I have a 270 WSM in a CRPF, and a Classic that was originally a 7-08 (now has a 257Bob bbl).
And the opening (ejection port)in the WSM action is over 1/4" longer than the 7-08 action. The overall action seems to be about the same length.
I did not take them out of their stocks, but it looks like there may be more differences than just the magazine boxes and the follower.