Each file is around 350-650 MB.
This is the media information from the Files:
How could I better archive it?
Easily convert & archive a bunch of low res Video CD DAT files MPEG 1/2 to newer better format such as MKV or others?
Using ffmpeg, a free command-line tool, you can convert these DATs to MP4 (or MKV):
ffmpeg -i input.dat -c:v libx264 -crf 20 -c:a aac -b:a 128k -movflags +faststart output.mp4
Your VLC output doesn't mention it but if the inputs are interlaced (likely), then use
ffmpeg -i input.dat -vf yadif -c:v libx264 -crf 20 -c:a aac -b:a 128k -movflags +faststart output.mp4
When you say archive, do you mean for long-term storage, such as in a library or museum? If that's the case a lossless, well-documented, open-source codec and container is what you want. FFV1 in a matroska continer (.mkv file) is my preferred archival codec / container format, and it's gaining popularity in the GLAM sector.
Once again, FFMPEG is the tool of choice for making these–FFV1 is a codec developed by the creators of FFMPEG. A good page on how to encode FFV1 here, and an example would be:
ffmpeg -i input_video.dat -c:a pcm_s16le -c:v ffv1 -level 3 -coder 1 -context 1 -g 1 output.mkv
For archival purposes I would not de-interlace because of the loss of resolution, and because it alters the source substantially.