I just made an EZE-GRU-JFK connection in less than 15 mins. Super easy, no immigration/customs needed. just a quick security check with no one in line. I was dumped right back out airside in T3, or was also given an option to stay airside in T2.

I think this connection is more than possible. I know MCT for I-I for for Oneworld is 60 mins. I had 55 mins scheduled layover time and i still made it thru to T3, to the LATAM lounge for a shower, some snacks, picked up some water/coco water and got back to my AA flight when they were calling boarding.