Why in the world wouldn't a 738 be okay for LAX-HNL?
Air Pacific flies from Honolulu to Fiji with 737-800 series (6 1/2 hour flight) -- going on to Sydney (3 1/2 hours) one NAN-BNE flight (2 1/2 hours) as well as Auckland, etc.
No 757s in the south pacific/Australia in pax svc, which is perhaps why the 738 is favoured here.
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Glen,
QFAA