The Illinois Railway Museum of Union, Illinois, is the custodian of a significant collection of original Pullman plans. But there are gaps.
See the webpages for the
IRM - Pullman Library. Make sure you read the several linked pages; these explain the extent of the collection, how to obtain reproductions, etc.
You will need to identify the order (or Lot) number to help find if the collection includes material of the car you are interested in.
Maybe your team has already been in contact with IRM and its Pullman Library.
Brian Norden