Without any research, I can only say I would be pessimistic about doing a int'l to dom connection with that short time period even if it was in the same terminal. Add to the fact busy travel day/ busy time of day and even if your wife is in 1st there may be a loads of other passenger from other int'l flights waiting to go thru customs/immiagration.Hopefully there are flights later into ORD on UA but hub to non-hub would favor DL over UA having later flights. She could standby for that flight but I'd book a later flight if it was me.