Just to save you time, you cannot merge laserdisc chroma with DVD/BD luma. The restorations tend to stabilize, realign and sometimes de-rotate cells.
Attempting to directly use the chroma channel will result in colors bleeding across lines.
You can try to use ColourLike and other tricks to color correct, but even then since we've seen repainting going on, the luma AND chroma will be altered in those areas creating incorrect colors.