Of course an 850 pax machine wouldn't be built for the long haul routes. They would be high density machines like the 747s within Japan (if we remember).
Why of course?
Which airplane has the most seats?
NOT Japanese domestic. ANA had 594 seats on 747, but does not now have them.
The biggest plane now is Corsair 747-400. 587 seats. Including 558 economy and 29 premium seats.
And Corsair 587 seat 747-400s do fly long flights. Indian Ocean, I think.
The largest number of people carried by 2 engines is Japanese domestic. 524 seats on 777-300 non-ER, including 503 coach and 21 business class.
But Air France 472 seat 777-300ERs come close. And fly long distances, like Indian ocean.