If we go conquest...
Well that makes the North, the Vale, and the Stormlands really viable... especially the former and latter of the three.
The North, due to being an ancient autonomous empire with a lot of cultural similarities to the Dawi, also terrain and lack of political squabling as advantages
The Vale: Mountains... Mountains a plenty... Well that and the First Men of the Vale still know some Runelore, which while the Dawi may not be able to teach them Ruhn Lore, may actually lead to the two guilds/House Runestone kicking off a 'rune-race' like the Engineers Guild and Nuln.
The Stormlands: They're essentially Tall Dawi with a little emphasis on the grudges; less dangerous terrain (pretty much the Black Mountains), and a large market of non fanatic Umgi.
That however also rules out the Westerlands, Riverlands (not exactly dawi terrain regardless); Dorne or the Reach.
The westerlands is extremely overpopulated no matter the timeline, and all major lords make their holds in the local mountains that they also mine for gold. They are the dwarfs of GOT, just with an Elgi complex; and regardless would be both prejudice and concerned by us.
The Riverlands is a basket case ruled by a poor mans norscans with no viable mountains...
Dorne is not just prickly in this timeline, they are far too unreliable, scheming, and not to forget livid - that the Valyrians are attempting to take over westeros, much like they tried to do to the Roynar. They don't have Doran to keep them in line; only the fear of dragons. They're essentially the border princes, going to war with anyone because of grudges and spite they have with their neighbors; something we dont need.
The Reach is ruled by fanatics (even if the Gardners are sane, the Faith is not), and have no viable mountains.
And for anyone thinking of working with the Targs regardless of timeline...
You know Aegon's mandate/demands. And Dawi, do not kneel!
Actually, one option that I'd really like would be Beyond the Wall. I know it would be basically rollplaying as Kraka Drak, but it certainly wouldn't be static