Take a real good look on your '30-'31 at the rear door (B) post and the internal framework that Brookville duplicates from the original Ford A. All of that metalwork has to be cut free and move rearwards. Then you will have to make a recess for the door rear skin to fit into to 'flush' it out. While it is very possible, it is very time consuming and quite costly if others do it for you. I have seen a couple of roadsters done this way - one was well done, and the other, well let's just say, one was well done. Lots of cutting, metal shaping and welding plus adding a lot of prep for painting above and beyond the Brookville built-in screwups and lousy body conditions. I considered it then said "I have had enough"