On page 146 of the 1934/35, 40 series shop manual it states, "The wooden frame work of the body when assembled is sprayed with an asphalt paint." I own a 1934, series and have found this to be true on all sides of the wood including all the wood found in the door. After 80 + years, the paint does show some deterioration. When restoring my doors I removed all the wood that was possible, sanded all the wood down to bare wood and painted it with a quality primer and top coat. On page 27 of the "1934 Fisher Body Service Manual," it explains how the diagonal front door stiffener rod is used to adjust the lower lock side of the door to align with the body contour. Since you have the door panel removed I suggest you restore or replace as much of the wood you can using quality products. Talk to a local cabinet maker and a local paint store for their advice. Good luck.