There is a major reluctance world wide to put 757 guys on the 767
Not with AJX. They accept the B757/767 on your licence as being type rated, whether you've flown the 767 or not. There's no great excitement because the 757 isn't a 'widebody' and there are pilots here that had only flown the 75 and not the 76.
Couldn't get in as a DEC as I'm 250 short of the 3000 PIC.
That is absolutely the reason they would not have accepted you in the past. The Japanese are so literal when it comes to these sort of things that 1 hour less than what's required will see them saying 'no'. Nowadays, as I've said previously, they'll want you to have a JCAB ATPL, >3000 hrs PIC on largish aircraft AND a B757/767 type rating to join as a DEC. I know that none of the recruitment agencies have this on their websites but, then again, they wouldn't, would they.