I would start with an Intermountain PS1 50' Single Door Boxcar, You would have to increase the door opening to 10' to accomodate the 10' door that was installed, also the side sill would have to be removed and almost full length deeper side sill would have to be installed. (Kadee has a car with the correct side sill but the opening is only 9' but the ABS plastic is much more brittle than the Intermountain plastic).
The door that is available can be purchased from Accurail.
Thank god you did not want the next group of cars in the 13000 class, those would be a real bear to kitbash.
Rick Jesionowski
Rule 1: This is my railroad.
Rule 2: I make the rules.
Rule 3: Illuminating discussion of prototype history, equipment and operating practices is always welcome, but in the event of visitor-perceived anacronisms, detail descrepancies or operating errors, consult RULE 1!
https://frisco.org/mainline/2015/01/21/boxcar-12050/
These were built by Pullman-Standard as lot 9467, commencing in early 1970. They were originally in yellow with black lettering -- in which form they appeared as boxes of promotional matchbooks which are not difficult to find on eBay. (There is also a 'red' version with the desired style of lettering but it isn't that series of car!).
Apparently when repainted to the red scheme they received updated plug doors.
I leave it to the serious model community to list accurate models, or sources for the improved doors.
Yet another one for my Forum friends. What would be the best options for modeling this car (http://www.rrpicturearchives.net/showPicture.aspx?id=5178528) in HO scale? I am looking a purchasing a rare decal set for another project and it has this particular car as one of the modeling possibilities. Thank you as usual for any assistance that can be provided.