I guess you really need to identify the facility that will / can make the computer to film transfer for you, and go and talk it over with them as early as possible.
Your client should be able to steer you towards a suitable (unless you’re expecting to arrange and pay for that?) as well as where the film will be projected (am I rash in presuming film and not Hi Def?)
There are a number of “standard” film definitions – they can help you to choose. You’ll also likely benefit greatly from what they can tell you / show you about how colour, contrast and movement translate to film; i.e. the difference from how it looks on your monitor to how it will look projected.