Did you have to rework the magazine or was it a simple barrel swap?...Check GUNS INTERNATIONAL.
FWIW, I located a left handed Winchester M-70 in .338WM on the above mentioned site. I then had the barrel pulled and installed a Krieger .458WM barrel. My very good P/H friend in Zim has been using this rifle as his "Stopper" since 2002.
...No changes other than the barrel swap. The magazine and follower were examined for any rough edges and pollished. The feed ramp was also pollished. Rifle re-assembled and test fired for function.Did you have to rework the magazine or was it a simple barrel swap?