By experiment, I found the Lee-Enfield (Mills) web sling will work quite well on a Krag.
Of course, I did not subject it to the trials of campaigning in the Philippines.

The British web sling is practical, inexpensive, and can serve as a 'shooting sling', as well as, a 'carry strap'.

Unfortunately, the U.S. Mills web sling, IMHO, was just plain 'goofy'. (Because of its narrow 'hooks', your sling appears a bit curled, even though it is dry).

BTW - The leather m-1887 sling intended for the Krag really appears to be in the neighborhood of 64 1/2 inches in total length.