In some finishing/compositing apps, there are filters that enable you to match the look of certain types of stock grain, as well as tonal-range.
(as digital allows MANY more colors I believe)

We have a member here at SM who runs a site dedicated to compositing, and he would probably be your best bet for a qualified answer.

His mane is Paul, and you can find the link to his site (VFXTalk) in the SM links database.

You could also ask Brian E. as he has done some VERY convincing composities for his reel that look like film to me, so make sure to ask him as well!

Good luck!

PS, PLEASE feel free to post your findings!