Being put on a later flight is fine so long as you don’t mind what ever seats are left over at no notice (thinking centre down the back).

MST (min sensible time) as opposed to (official) MCT should be factored in. For me, a > three hour connection is needed if US immigration has to be done. I have experienced 2 hr immigration queues at LAX, SFO and JFK. The immigration line up guards didn’t give a rats about people pleading short connections and those lined up were in no mood to tolerate those wanting to jump the queues.

Yes, IMHO, 1:45 is unrealistic MCT.