I used Trans-Tint dye (Amber Brown) to color all the new parts. When dry, everything received a light sanding. I followed this with two coats of cedar oil, which gave the inside a nice cedar scent.

    Here's a closer shot of the new parts fitted and finished.

    The old door panels seemed to be 3/16-inch thick veneered plywood that had seen better days. There were splits in the veneer and the finish was dull on both. I made new 1/4-inch solid panels from quartersawn white oak that I resawed from rough 4/4 stock. Each panel consists of three pieces. The two outer pieces of each panel are bookmatched. The center piece of each panel came from one board. Since I had to use three pieces to make the panels, I decided separating the outer bookmatched pieces the way I did would give the appearance of continuity.  
    To finish the door panels, I started with a coat of Watco oil on the outside faces only. Next, I applied the dye on both sides and let it dry. The inside surfaces received two coats of cedar oil while the outer faces received a coat of the new Zinsser Bull's Eye French Polish. When the shellac dried, I followed with a coat of Johnson's paste wax and buffed to a beautiful shine.
    After cleaning and waxing the door frames, I installed the new panels to the back of the frames. I cleaned the tarnish from the brass keyhole covers and polished them. Now the doors were ready to hang on the completed cabinet.