If your having to pay someone to set the barrel back I would buy a new barrel and have it done. If your doing it yourself and there is plenty of tennon left I would say go for it. I dont have the chamber specs infront of me, but you'll have to remove enough old chamber to get rid of the 30-06 so it can be punched out for the shorter fatter WSM.
Thanks for that feedback, if you actually have to remove enough of the chamber to erase the 06 completely, then I don't think it's feasible. I just want to do something with this takeoff I've ended up with, and I don't want an 30-06.
Most factory barrels there is enough tenon that you can set it back once. By that I mean cut the existing threads off and re-thread for a blueprinted action. If you have a lathe and are doing it yourself it would be good practice.
I keep all my take off barrels until I get a full garbage can of them. The steel recyclers give my about $50 bucks for them. Stainless .224" bore barrels make good pillars and brake blanks.