Ah, that makes more sense.
As far as using such a project for archival means, have you first looked into other forms of media storage (such as optical media or tape drives)? You could also look into storing the same data in multiple hard drives (as e.g. a RAID setup), so that when one hard drive fails you can swap it out for a new drive and you won’t have lost any data.
As far as codecs, yeah that’s slightly more challenging. I would store software in the archive itself that can decode those videos into RAW format or store the videos as RAW altogether (considering the relatively small size of the videos). That way if you need to grab the videos in any format, you could run the video decoding software in the archival system to RAW and then encode the RAW with your modern video format of choice.
Back to the project itself, now that I know what kind of media you’re working with you won’t need a 6K projector. Just an off-the-shelf business HD projector would be plenty, maybe even a touch overkill.