Moth3r said:
Starting with the output from the g-force script, run it through a very strong denoiser to completely scrub all grain - but generate a "difference" clip from the source and cleaned video. Apply the subtitles, then overlay the difference clip. This is essentially adding the grain that was removed back in, only this time it will be on top of the subs.
Smart. It makes the subs more authentic than with the method I've suggested.