One word of advice, if I may: the "firewall" (the part to which the seat will be attached) had not been made out of wood, but out of fabric. Rule of thumb: If the aircraft is covered with Flugzeugstoff, then it is likely the "firewall" would be covered with lozenge fabric as well. If the wings were not covered with Flugzeugstoff, but painted with the standard colours (green and mauve), the firewall would be CDL.
Stefan