From what I see, it looks fine. Your breakdown graphic (above) is right and your last shown capture/adjustment (top page) reads fine.

My eye-dropper (averaging 5x5 area) reads (RGB):

WHITE - 253,253,253 [±1]
BLACK - 3,3,3 [±1]
GREY - 191,191,191 [±1]

The only problem I see (and I don't know if that's fixable) is the blue's wide variation in the mixed colors -- demonstrated in my above color-separation strips analysis. The other colors vary, too, but that seems to be the nature of the analogue beast (more so with consumer equipment). :)

Aside form all that, I noted my concern to not get too close to the bottom & top limits (0 and 255) to assure the media proper doesn't go out -- unless you can easily test it throughout the length of the movie(s). Of course, any stray pixels that differ from frame to frame shouldn't be a bother and should be allowed to be clipped at those limits.