What I did with my 1929 Chrysler '75' roadster in order to title it was to trailer the vehicle to the DMV with all of the paperwork. I showed the clerk the FEDCO number and they titled it to that number. Show the clerk the car's FEDCO number and the paperwork with that number on it and explain your theory about the numbers being subtracted from the earlier registration/title. My Chrysler book shows the 1927 Model '60' engine numbers going from H-21001 to H-72800.
I just got a late Christmas present...I just saw a 1931 Dodge Brothers DH6 roadster for the very first time. I went to the Dodge and Dodge Brothers forum and there it is! I know that it may sound strange that I would consider it a gift just to see it, but I am strange anyway.
Oh man, that's the first real '31 DH6 roadster I have ever seen! BEAUTIFUL car!! Where are you located? I would love to get together with you and compare notes on our cars. From the look of the car, you don't need a thing as far as parts go.
Can we see photos of the car? I may be able to help you with parts and information. As "nearchoclatetown" said, the original brakes should suffice if they are adjusted properly.