It is possible to purchase just the 'swing up' peep for the 1902 Krag sight from S&S Firearms (Glendale, N.Y.).  If you need a bigger aperture to use this feature on your 1902 sight,  obtain a spare 'peep' plate.  Drill the poorer condition plate to increase the aperture size.  Save the better plate for originality.  Also, low power readers with high impact lenses can be used as Shooting Glasses to bring sights into sharp focus.  The target bull may be fuzzy, but that doesn't matter much.