Don't think it has been done!
Just checked to see if a 300 WSM would feed out of the mag. I'll be damned, they fit in just fine and slide forward to feed in the center of the mag. Other than some serious bolt face work and a rechambering job. Port timing and recoil spring replacement, beef up the OP rod, change gas piston , etc........etc.......etc! All it would take is a very big chunk of change $ !!
Now the next thing what pressures will the M14/305 takes before it comes unglued. Personally I think the WSM pressures will be far in excess of what the M305 action will take. Good luck finding a gunsmith willing to take on the project. Located a smith advertising on the internet that converts M1 Garands to 338win. Mag. Your dream maybe a possibility. Good luck and keep us posted.