Has anyone ever opened up the bolt face of a Weatherby Mark V for a larger cartridge?

I have a Fibermark in .340 Wby Mag with a shot out barrel. I'm kicking around my options for a different chambering, but am wondering if I am stuck with the 0.512 cartridge base. Looking at the bolt face, it seems the Weatherby design might be a tough one to mill a bit larger. I figured I'd ask the experts before I ruled it out entirely.
[Linked Image]