GUTS:  If the commercial Lyman peep sight is left on this 1899 Krag Carbine, it will require altering any Krag stock to allow clearance for the Lyman sight.  (You don't want to do this inletting on a desirable Krag Stock).  If you remove the Lyman sight, which is collectable in its own right, You will have ugly threaded holes in the receiver, which are not original.  I would recommend you contact one of the gentlemen listed in the KCA classifieds, who sell Krag parts, and see if they can help.  You need a Krag carbine front sight blade (to replace the Marble's blade).  You need a 1901 Carbine rear sight ladder and slide.  You need a serviceable Stock.  (You might consider using a Krag rifle Stock that has been cut-down to Carbine or sporter length).  Any of these parts are going to be hard to find and expensive.  If it is decided to keep the commercial Lyman sight on this Krag, leave the front sight as is.  Also, don't bother completing the 1901 rear sight because it will block the view through the peep.  If it were mine, I would obtain a cut-down rifle stock and just assemble everything as is.   

I think the cheapest way to get the thing shooting again would be a Boyd's stock. Sure quality and ease of fitting is sometimes problematic, but probably no more so than any other, and a decent mechanic should be able to accomplish it. Sell the 1901 C sight base and handguard to help defray the cost of the repro stock. Keep the Lyman sight on it for that represents almost as much value as the rest of the rifle.

Of course, if the bore is "frahundsed" just hand the whole thing back to your friend and tell him to part it out, for then it becomes economically imprudent to do anything with it. A new barrel will cost 200 beans- darn near what a decent 'shooter' can be had for.

Guts:  If your Friend's altered Model 1899 Carbine is in shoot-able condition (and most Krags are), a cut-down rifle stock provides an easy and not too expensive solution ($90-$125).  I would contact one of the two gentlemen in the KCA Classifieds, who sell parts, and let them know your situation.  They may have a cut-down rifle stock or altered carbine stock that will do.  You can also check GunBroker for parts and wood.  To work, a stock would have to be 'notched' for the #34 Lyman (use the broken stock as a pattern).  Don't go carving up any really nice Krag Stock!  A cut down Rifle stock and Rifle barrel-band/sling swivel will fit and look good on a 'carbine'.  Here is a picture of a couple of 1899 carbines I have that became 'Deer Rifles'.  The top one is in a cut-down rifle stock and the bottom one has a thinned-down carbine stock.  This was the fate of many Krags and is a part of the "Krag Rifle Story".