Sounds like you need one of the Yugoslav modified stocks and handguards. They cut down some original German stocks about 1/2" for use with re-barreled K98k's since Yugoslav replacement barrels were about that much shorter. Front barrel step will sit under the upper band with an original length K98k stock. Interestingly, the Yugoslavians made replacement stocks for the original length rifle barrels in both cupped and flat buttplate versions, and this is what you show in your photo. This is the dilemma when trying to use Yugoslav stocks for a restoration. Stock and barrel lengths involved need to be known.
Sounds like you need something like this from Numrich...
https://www.gunpartscorp.com/products/1478680
Make sure you get the proper handguard they list for it as well.