In my humble opinion, I would do as Butlersrangers suggested and go with the 30 inch Criterion barrel.  The CMP would correctly install the barrel and it would be indexed properly for the extractor notch.  The reproduction front sight post would be far better than installing a 1903 sight... and would only aid in accuracy and value.  Although the rear sight holes are not the same thread as the originals, replacement screws would work fine and the CMP's installation would insure a good fit of the sight.  A Win/Win!