There will be no fitting required with a finisher stock and little wood to metal fit on a unfinished stock. The acception being the barrel channel.
I agree try oil is a good readily Atainable finish. Lin seed and Lin speed oils are also long standing favorites. More recietfly people have discovered my favorite Tounge oil. But even polyurathayne and she lack have been used with good results.
Like all such thinks the devil is in the details. Details are prep work, as poor prep with make for a poor finished product. Sprnd the time to properly ready the wood for the finish you will be rewarded with a beautiful long lasting stock set.
Good luck,
CW