I do not believe Angmar poses a serious threat. Sure, there are fell beasts, but the Nine have fallen, and they are leaderless. I have heard no reports of them leaving Angmar to invade other places, so we should be fine on that front.
However, we must consider this: Gundabad has not been controlled by Dwarves for a looong time.
It is crawling with orcs and would be virtually impossible to overtake.
I propose instead that we attempt diplomacy.
Not all orcs are controlled by Sauron. Some, like those who used to be controlled by the Goblin King, instead follow their own leaders, not the Dark Lord. Though many do not respect the Orcs in the slightest, through study we have found that they do have a potential for good. Those brought up far away from corruption have a sliver of goodness within them: they don't like how Sauron controls their people, but they are forced by fear to obey.
I propose that we give these Orcs, those who want Sauron gone but have no means to that end, Gundabad as a homeland.
They can settle it, depose of those leaders they do not appreciate, put strong, just ones in place, and perhaps even join the greater world community one day in the fight against Sauron. The steps towards conversion of Gundabad from the hell it is now to a more civil state could be led Electric_Ice, Warchief of the Trolls, who has been able to be reasoned with, as proven with the treaties of Forochel ((I mean I expect there is a treaty as most respect that land as the home of the Trolls, ruled by Electric))
((I'm not sure if these 'good orcs' are really a thing, I'm not too well versed in the biology of orcs, but if it is a thing, that'd be super cool, and people could start being Orcs instead of Dwarves, Elves or Men, but not crazed or evil. There could even be a Warchief of Gundabad.))