In all honesty, I think picking out actors for K2 is a lot more easier then K1. I would obviously hire Sara Kestelman as Kreia because I think she is the one and TRUE Kreia out there.
Plus she looks like Kreia as well. As for Brianna, Grey DeLisle has both the looks for it and the voice. Sure, her hair isn't white, but Keira Knightley's hair isn't white either.
Atton is simple and easy. Nicky Katt for the win. That guy looks, sounds, and acts like Atton Rand. Plus, the dude has been in a couple of films over the last few years. He even appeared in The Dark Knight as a SWAT Member. As for Mical, I'd hire Greg Ellis for him. That guy does have experience's in the acting industry.
Sion would be Louis Mellis, Daran Norris would be the voice for Goto as If I was doing a KOTOR II trilogy, Goto, T3, and HK-47 would all be CGI. And the voice's of HK would be done by Kristoffer Tabori. I haven't thought of someone for Mira or Visas yet. And the Exile remains to be a mystery. And I'm probably the only one who opposes Ron Pearlman to be Mandalore. I think John Cygan should be Mr. Mandalore.
Well, that's my list so far.