Francois:  Your Krag has to have an interesting, but untold history (a 'sporterized' U.S. Krag that got to Europe).  More detailed photographs of your front sight, diopter rear sight, and stock would allow forum members to offer insights about your rifle.  How long is the barrel on your Krag?  You said the front sight is a Lyman.  Is it possible that the front sight base is a 1903 Springfield 'banded' sight base that is holding a Lyman blade?   I think your diopter sight is an early Lyman 48k.
  I believe you would like your Krag to look more military.  Probably the most practical route is simply to replace the stock with a rifle stock that has been cut-down to carbine length.  During the 1920s to 1930s the U.S. government sold off the Krags to citizens.  To make the rifles more marketable, some were altered at Benicia arsenal in California.  The rifle barrels were cut to 22 inches, a 1903 Springfield front sight was installed and the rifles were given a carbine stock or cut-down rifle stock.  These altered rifles are often called 'DCM' or 'NRA' carbines.  They were not a military model, but an alteration for the Civilian market.  They are attractive and practical.  I am attaching a photo of a Krag that was sporterized.   I replaced the stock with a rifle stock that was cut down and put a hand-guard and rear sight on it.  It has the appearance of one of the 'DCM/NRA carbines'.  Also in the photo is an 1899 Krag carbine.   

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