The “Old Film” filters are effects to make videos looks like they are old. They ADD dust and grain, etc. So those are not what you want.
I would expect that the “Film Restoration” video would apply to black & white content - especially the grain reduction part. You might also need to apply color grading to make the black & white look right.
I don’t know of any video tutorials that are specific to B&W film.
There isn’t much available for written documentation for Shotcut. Your best options are reading posts on this forum and watching tutorial videos on YouTube.