i am by no means an expert on int'l travel, but based strictly on the layout of the airport alone, i would not think that 1:17 is sufficient time for that connection. coming in from LAS you will most likely arrive in T7 or T8. international flights depart from the other end of the airport. i just dont think that is a smart idea...especially if you cant get the two linked and you arent checked-in through for the whole trip.

edit - i just read in another thread that UA international flights leave from the regular terminals, not the international terminal. this might make things a bit easier on you...sorry for the misinformation