OK since I don't think either of us has access to AC flight planning software, let's make it simpler.

Boeing 737-800WL listed range: 3,115NM. Flown by WS to Hawaii X times daily.
Airbus A321 sharklet range: 3,200NM (wiki says with 185 pax)
Airbus A319 sharklet range 3,700NM (126 pax)

ETOPS fuel requirements would be extremely similar between both 737/320.

If the 738 can do it, so can an Airbus.