Sometimes groups ended up on secondary trains for various reasons. However, effective 12 Nov 68 the best schedule was Train 55, the Pennsylvania Limited. It departed Paoli at 12:01 a.m. Do you recall what period of the day you began your trip? It was due into Chicago at 3:10 p.m., connecting in Union Station with the Streamliner City of Los Angeles / City of San Francisco at 6:00 p.m.
The best train from Paoli, as mentioned above, was the Broadway Limited, which was the last full-service train on that route. It departed Paoli at 7:03 p.m. and arrived Chicago Union Station at 8:40 a.m. For space availability and to reduce the stress on group leaders in Chicago, you may have continued on the Streamliner City of Portland at 3:00 p.m.
In earlier years, the Pennsy had waves of trains from Paoli and I doubt whether they would have booked a youth group on the sacred Broadway,