Bah, I’ve worked for hours on this, and nothing fits. It’s fine though, I’ve realized that ‘Finn’s familiar with the weapon system, he worked on the base’ is audibly identical to ‘Finn’s familiar with a weapon system, he worked on the base’.
So I’m fine with leaving it as it is, and leave it up to interpretation as to whether or not Leia was aware of its existence before this moment.
I think it’s pretty great. The mouth editing could be slightly better, it seems like the mouth moves down a bit at the beginning of “a weapon” and the shot looks a bit blurry (but maybe it was a bit out of focus to begin with?). Also the shot of Leia just before becomes choppy for a few frames, if you slowed it down it could use some frame blending to smooth it out.
It is a bit odd to just casually mentioning “the base” though, as if everyone involved knows there is one. Perhaps it could be changed to “their” base or “a” base?
I also like your idea on how to include the deleted scene, I think it could work well.