Reproduction Krag front-sight blades can be purchased from S&S Firearms, Glendale, N.Y. (Their Catalog is view-able online).

The Krag front-sight pin is tapered. It should be driven Left to Right. The rifle blade (alone) is normally .413" tall, when measured out of its base.

A taller front-sight will lower the point on the target where your 'cut-down' rifle groups.

Since this Krag's barrel was shortened, the front sight base was undoubtedly re-attached.
The base is very likely shorter than it was originally.

You might be further ahead just making a new 'taller' blade (out of a coin, sheet metal, or brass) and experimenting.

It is unlikely an original blade will be quite the right height, because the location and base height have all been changed.
These changes have altered the 'sighting angle' to the point you are shooting a foot high.

Maybe the gunsmith, you have working on this Krag, can estimate, make, and insert a taller blade, while he has your gun?