It looks like the Climax roof will be my stumbling block. Ah well, another potential project pushed to the back burner.
Gene, doesn't Al offer a radial roof with his C&O USRA SS box cars? I think this is a flat kit.
I have a 40 ft. roof like the one you need on a Yankee Clipper car. Probably a C&O 1932 ARA box car. Could be NKP. PM had this type of roof too.
There may be a good picture of these cars in the soft cover C&O freight car book.