The 7WSM has a longer base to shoulder length than the 270WSM. You would have to neck way up and then neck down to create a false shoulder or neck up and jam the bullet hard into the lands to set headspace.
I think it would be easy to do, I looked at specs last night, you are only moving the shoulder .05?" Now I cannot say if a false shoulder is needed or just a hard jam.
Cases are the same length upfront.
I think I would just load a couple up jammed and shoot them. You're not going to blow anything up. Case dimensions identical, other than shoulder needs to move .033".
I'm sure someone has tried this, I'll bow out.
It is best to create a false shoulder. I have some 300 wsm brass sitting on the bench for this reason but I ended up with about 400 loaded rounds of copper creek and corbon ammo so that got put on hold.