You are already 737 captain, so next logical step is not FO, but wide body captain. Not sure you got the minimums but I'd give it a shot on NTR DEC for 777 or 787. Believe me, you do not want to join as FO, the money and the big jets dream will not compensate your peace of mind. So in my opinion you should stick to DEC no matter what (even A320), too risky to join as FO and for any stupid reason get a red ink mark on your file which will make your upgrade back to the left seat impossible.