A quick look at the payload range graphs shows that:
789 (at 254T) can carry 280pax + 35T cargo 6000nm (more than enough for FRA-LAX
789 can carry 325pax (bit of a squeeze) + 27T cargo 6000nm
781 can carry 325 pax + 10T Cargo 6000nm
359 (at 280T) 325Pax + 25T Cargo 6000nm (it is limited by its Max structural payload not fuel)
If LH can fill the cabin and have regular cargo of 25T it would seem to be the pick, but otherwise, because it must be a lot cheaper to fly a 254T aircraft, than a 280T aircraft, I think the 787 is in with a chance.
When you look at Airbus and Boieng specification. B789 MZFW 181,436 KGS OEW around 127,000 KGS it is around 54,000 KGS of payload. A350-900 MZFW 195,700 KGS OEW 135,000 - 142,000 KGS will carry 60,000 - 53,000 KGS so your numbers are incorrect!
OEW depends on carrier and A/C configuration but generaly, A350-900 can carry more payload in every scenarios!