Has anyone ever considered that the 737 can be fitted with 9 (yes 9) auxiliary tanks giving it range enough to take it from the west coast of the US to Japan? ANA has a scheduled service using a 737 in all business (or was it first :-/ ) non-stop going from Japan to the US. I believe the 737-700ER has the range of 5510nm.
So if you want to make the plane go farther just make sure that all the fuel tanks add up to 10,707 gallons (or 40,530L)
That's insane

And it is cool to see the old 767 competing with the 777s, the A330s and the A340s on Transatlantic flights.
I even trust the General Electric CF6s of the 767s more than I trust the Trent 895/Trent 892 on some Triple Sevens.