Go 767
Unfortunaly the aviation business is full of so much ingrained rubbish about what people can and can't do you need to get the biggest type on your licence as soon as you can.
I can remember being told that I was unlikely to be able to fly a turboprop when I was flying piston twins, then when I got the turboprop tick in the box it was "you won't be able to fly jets" now I have flown the BAe 146, B737 & A320 for about 5000 hours in command I am told only those who have previously flown wide body's can fly them despite the fact that I have done the ETOPS & MNPS thing across the North Atlantic with the 73NG.
So rather than battle with prejudice and bull get the 767 and at lest you will then have the wide body tick in the book as soon as you can.