I would pursue the 737 NG job. There are over 25 ExPat contracts out there for 737 NG Captains. The 767 is sadly a dying breed and maybe 3-4 contracts currently out there. You will also probably fly more hours and you definitely will become a better pilot with the 737 NG. You will do 4-5X more approaches and landings in a 737 NG job and it will be a stepping stone to a larger Boeing aircraft with NG technology much mre modern than the 767. I have flown both and jumped at the chance to change into the NG given its HIGH Marketability. Best of Luck!