I see a couple solutions -- (first I have to say how awesome it is to see the shot flipped) -- but I don't know the whole picture yet of what changes are being made, so maybe these solutions will help and maybe they won't.
I don't like the idea of blurring Sam J's lips. I think we need to work in ways to cut around the problem and use only synch dialogue. So the problem comes from using that long beautiful master shot and making it match the dialogue.
Solution #1 is to have the line "He is a politcal idealist...not a murderer" play over the preceding Exterior shot. Then finish the line as we cut in but before any non-synch problems can be detected-- maybe a half a second or so.
Solution #2 is to move Sam Jackson's line "He was a jedi..." until after Palpatine's line. Let Palpatine's line be the response to the bearded guy and let it come when we cut inside, as Palpatine starts to talk.
I think that'll solve things. I even wish there were some silence between the lines-- silence that speaks volumes about the gulf between the jedi and Palpatine-- and about the graveness of this situation. But at any rate it looks great.
EDITED TO ADD: I know the logic may not seem crystal clear here, but I think non-linear dialogue often sounds more natural than A-B, A-B, A-B. So I'm suggesting that we do A-C-B-D. Like this:
EXT. Chancellor's office - Day
Beard guy (V.O.): He is a political idealist, not a murderer.
INT. Chancellor's office - Continuous
Palpatine: But more and more star systems are joining the seperatists.
Mace: You know Dukoo was once a jedi. He couldn't assassinate anyone.
Palpatine: ...I don't know how much longer I can...
Mace: If they do break away...
Palpatine: My negotiations will not fail...
Mace: If they do break away...
I'm not sure I understand the flow of this dialogue entirely. I think we get to the "My negotiations will not fail" line a little fast. Maybe Mace needs to finish his thought first and then have Palpatine's line. But then I don't know the footage or the whole scene yet.
I just know, using what's there, you can get through the master a little easier with my suggestion. I also think the master can be cut out of sooner if you have coverage of some of the lines, say a shot of Mace saying his line or any part of his line so you can cut out of and then back into the moving master.