Tommy,
For an aged patina on your plane after you have stripped off the Japaning, apply a rifle cold-blue solution (more gray than blue) and use a fine abrasive pad to reduce it to the color that suits you, then coat very thinly with TruOil stock finish, literally a wipe on/wipe off application. After a few days to cure completely, buff to suit. You end up with a very attractive dark patina.