B7a & BS class box cars

[nw-modeling-list at nwhs.org]

Just incase folks missed my earlier post. I want to model some N&W class
B7a's and BS class box cars. They are both 40ft cars. In HO scale. What
would be a good starting point to do this? Red Caboose's AAR box cars?? I
would appreciate any help in this project.
Thanks,
Fred Mullins
modeling the Atlantic & Danville
remember "For Service See......the A&D!"