I would not stain that beautiful Walnut! Are you going to use Walnut for the base too? If so, I would glue them together first, then soak in a 50/50 mix of boiled linseed oil and mineral spirits. Wipe off the excess, then let dry for 24-48 hours. Then you can apply what ever topcoat you want. That Walnut will look so great with oil rather than stain!