One interesting aspect of old NTSC sources is the wider colorspace. This was only changed in the 1990s:
https://en.wikipedia.org/wiki/NTSC#Colorimetry
For example the first seasons of Star Trek DS 9 use the old colorspace. This was not corrected for DVD release, even on the PAL versions. That why the colors look so unsaturated and off. We are viewing them on sRGB / EBU displays with a smaller color space!
https://color.viewsonic.com/asset-files/images/what-is-color-gamut-3.jpg
Interestingly, this NTSC colorspace is very close to the current DCI-P3, used for 4K HDR TV.
Just something to take into account when preserving NTSC masters. If the colors are really off, it needs colorspace conversion. There are some Media Player Shaders that can handle it for playback I think.