Actually, if you want the "real McCoy", your best bet is to visit the Athenaeum of Philadelphia, as they have supposedly the complete set of ORIGINAL plans for Reading Terminal, occupying 10 file drawers (i.e. hundreds of drawings). Please see this link for more details:
http://www.philadelphiabuildings.org/pa ... .cfm/19662
Their website lists other collections related to Reading Terminal with additional drawings for the train shed, approach railroad line, and the 1948 renovations, plus some photo links and other published sources:
http://www.philadelphiabuildings.org/pa ... .cfm/20382
Good luck with your search!
-- Rick Bates
Reading Railroad Heritage Museum