Although it would take a while, I do think a renumbering process would hugely benefit Go North East.

It's not a completely foreign process to bus operators, either. In fact, Anglianbus renumbered their fleet just two months ago!
Anglianbus' fleet was renumbered in the the same number series as the Konectbus fleet and both operators vehicles will appear on a joint fleetlist. To view said fleetlist, see link below:
https://docs.google.com/file/d/0B5hg4kGr...FEUkk/edit

Stagecoach manage it brilliantly, given that they have the entirety of the UK to consider with their fleet.