Actually, we saw Takei in that Voyager Episode, Flashback? Both he and Whitney put on A LOT of weight since we saw them in The Undiscovered Country. Other than that, they really haven't changed a whole lot. But, If you could get the actor that played Harriman and Demora Sulu back, you could have a good run on the B. Heck could have an "Admiral Chekov" giving orders. I think out of all of them, besides Nemoy, Koenig is the only one that still looks like he could play the role he played a decade and a half ago.