I usually try to book on one flight earlier to STL for International flights to give me some cushion. They will probably only put you up overnight and out the next day. Although with AA on board, they could fly you to Chicago and catch an earlier flight the next day. I doubt if there are any flights to Paris that you could catch from ORD same evening. They will put you up overnight and some meal $$.
If you cannot get them to change your ticket to an earlier flight to STL, you can always standby (and tell agent of your concern to improve your chances).
Generally 1 hr 15 min is ample time to make connections, even if a 45 minute delay. Longest walk (run) from gate to gate would be 15 min. - and probably shorter as I think PDX flights ususally come into concorse C and Paris flight ususally in same concourse.