As Jim said, resale value of sporterized M98 actions is a money-losing proposition. While you can find some very nice examples of finely made gunsmith rifles built on M98 actions selling for more, most M98 sporters fall into the $300 range +/- $50 or so.
A rifle chambered for an obsolete cartridge, like the 225 Winchester, will have a lower value simply because of the need to rechamber it prior to being able to fire it. Unless it is a really fine example of workmanship and excellent materials, it is worth about $200-$250 and absolutely no more than $300. Remember, you will have to pay someone to recut a chamber you can get ammo for.