Preserving the original leather sling is a great idea because the old dry leather will continue to crack and get damaged if you neglect it. Using a repro sling is great on a Krag but having an original sling on a collectible piece is even better.

There are many kinds of leather treatment waxes and balms available. My favorite (certainly not the only one) that I have used for years on leather boots, shoes, holsters, belts and slings is "Sno-Seal". It has beeswax and  other preservatives in it that soak into dry leather well and recondition it to look great. Nothing will heal a deep crack but something like this treatment will fill smaller ones and provide a moisture and lubricant that will keep it from further damage.

Look around and find what might work for you. The leather looks so nice when you recondition it. Use it liberally and let it soak in a few days before wiping the excess off. It works really well.

While we wait for one of our members to check the serial number, it is nice to see that your 1898 was actually made in the last few months of 1898 and is therefore an true antique for legal minds.
It matches, too, the cartouche date and makes the 1896 rear sight and handguard also correct for the date of manufacture.  Overall, it looks like you got a good piece for your efforts.

'King carp' - Your original Krag Sling was mainly a 'carry-strap' and not really a shooting aid.

The later 1907 Sling 'psteinmayer' suggests was designed to be an aid in the prone and sitting positions.

It would be interesting to see a close-up picture of your front sight protector. It may be an O'Hare or other 'custom' protector/muzzle cover that was favored by target shooters. These devices are rare and expensive.

BTW - The letters in your 1898-dated stock 'cartouche' are J.S.A., for Joseph Sumner Adams, Asst. Foreman - Assembly Room, Springfield Armory.

Here is a pic. Of the serial no. It would be great if there is any info out there on this particular rifle. The bore checked out at .307 and .300. My old 180 gr. Ohaus mold should work out for reloads I hope! It is a loverin style that works well in my 1903A3.
       Thanks again, KC

Your brass sight protector is the "common" rifle muzzle cap that is highly desirable and, when you can actually find one, sells for around $70 or more. I have worked hard to find and buy a few of these over the years for my Krags. Yours has a beautiful patina which authenticates it as original. There are reproduction muzzle caps being sold which are bright yellow and look horrible but, if you can't find or afford an original one, are nice enough. They sell for around $40.

This is a copy of a picture from this KCA photos page that shows the variety of muzzle covers used for different Krags:

Hello: thanks again for all the info. Its interesting about the one rifle being an antique and another modern because of its serial number. I have been trying to acquire this piece for quite some time and do not intend to sell it any time soon. It's funny this is the oldest U.S.
Military weapon I own and it was the previous owners most modern. I had to come up with some civil war items to get it. That took a lot of hunting around but I think it was worth it.

Thank you for your detective work! The layers of history are being peeled back.