The key difference between the two rifles will be the magazine box setup so you would need to worry about whether the mag box inletting is the same. The action is the same. The barrel profiles also appear to be the same (big bore DGR vs a .460 wood stock) so the barrel channels in the stocks should be very close. Another stock that might work would be one from an Accumark. The barrel profile on my .340 Accumark was a similar heavy profile to the barrel profile on a .460 Deluxe. The Accumark stocks and bedding blocks are set up to free float the barrel whereas the DGR stocks and the .460 Deluxe wood stocks are not, so that may also be a consideration for you.

I've never tried the swap myself. Maybe take your handy dial micrometer and go measure the barrel profiles of a DGR on a gun store shelf. Don't know where u are located, but Epps in Orrilia, Ontario has three DGX in .458 Lott on the shelf as well as at least one .460 MKV Deluxe. They are also a Weatherby warrantee centre/dealer so they could order whatever suits your fancy.