N&W B7a box cars

[nw-modeling-list at nwhs.org]

Folks,
    I want  to model some N&W class B7a box cars. What would be a 
good starting point model in HO scale to do this? I don't mind having 
to add some details?
Thanks for any help,
Fred Mullins
modeling the Atlantic & Danville
remember "For Service See......the A&D!"