I love Google, I do it to promote my self and when you are modeling you can use basic words to find out a lot of informtion such as by Googling:
print modeling agencies + NYC
Modeling agencies + NYC
Usually if the agency has print as a focus you can send pictures no matter your size.
Make a compcard, or put together some images and mail them to print agencies in NYC. Just google Print Modeling Agencies. These agencies might be a good choice to mail, or call or email them.