gunboat57:  That is a nice looking Sporter by the way.  Is there any screw or barrel band holding the barrel in its stock channel?  If not, it is likely cracks will appear in the stock in front and behind the magazine door and side-plate.  If only the trigger guard screws are holding the barreled action in the stock, the barrel will rise during firing and put a lot of stress on the stock in the magazine area.  (A temporary solution would be to wrap some paper around stock and barrel and then wrap some strong tape over the paper).  Your idea of fitting a metal blank into the dovetail and drilling and tapping a rear hole for the Krag sight is a good one.