I think he said in his videos that he’s not trying to match his scans to the Technicolor prints, but to actually restore the movie as close as possible to its original look. From what I understand, here’s what he did/is doing:
-scanning and cleaning using various prints as sources to get as much detail as possible;
-color correcting to match the actual on-set look;
-regrading (for which I suspect he has implemented the same processes he knows were used for the original movie in 1977).