Understood. Then what you have assembled so far fits your criteria.
Sadly there are no boxcar models that even come close to the New Haven prototypes of at era However, here is some existing era-appropriate NYNH&H rolling stock that is accurate or very close and should be both easy to acquire and reasonably priced either in primary or secondary markets:
BLW 2000-22 33' twin ribbed hopper
(photo)BOW 37106 NE2 caboose
(photo)BOW 37128 NE2 caboose
(photo)MTL 08500030 33' twin panel hopper
(photo)MTL 04500270 50' fishbelly flatcar
(photo)RC 16014 or 26024 40' flatcar 2-pack
(photo)
