As far as I understand @Alain_Oguse, the goal is to bring forth, in converted images, the grain of B&W film.
Generic approach: In analog/chemical photography, this used to be done by using directed light, whilst diffuse light was recommended for colour.
Specific add-on: In order to improve the effect, green light of respective quality will lead to less recorded photons on red and green sensor pixels. This can (and seems to) reduce destructive interference by red and blue pixels and interpolation in the de-mosaicking process. Using coloured light also makes chromatic aberrations less visible or go away altogether.
In reference to your questions @SSelvidge, we need to do two things that can be approximated by a) using a band pass green filter like the Hoya X1 and by e.g. moving the backlight away from the negative so that light does not reach the negative from wide angles but only from narrow angles.
Trying to approximate the effect - e.g. if you have no suitable B/W enlarger to modify - is best done with a short tele macro lens. See this post for a simple test with white light.
I also tried R, G and B light from an iPad to construct a colour image from B&W captures, also approximated as documented here.