I assume that your TRIM number on the firewall plate is 641 (Dubonnet Bedford cloth) or 661 (Dubonnet Face Finished cloth).
Original formula information for paint mixing is useless today...many of the component colors from when the cars were new are no longer made due to government regulation on chemical content. However, you can get your local PPG jobber to contact the PPG corporate Color Library for mixing formulas that use currently available component colors. The Library has original sample colors on file and uses a spectrometer and a computer to scan the sample and identify it's components. There is no extra charge for PPG performing this service, the understanding being that the jobber retains the mix info (it comes out in PPG component colors anyway) and makes the paint sale.
To do this, you will need the K-F paint number for Dubonnet (155) as used on exteriors. This is listed as being a non-metallic color in the Confidential Bulletins from Kaiser-Frazer Sales Corporation as well as the Service Bulletins for the color as used in 1949-50 model years.
One last thing...while the particulars of an automobile are of course, the choices of the owner(s), the PAINT number on the firewall will identify the exterior paintwork of the car as done originally at the factory. Incorrect color not only is a point deduction, it could also lower the resale value of the vehicle.
