If I’m not mistaken, if the Bluray were GOUT synced, one could apply these colors easily, right?
No, it’s not a matter of being sync’d. The GOUT appears to have had a single color correction applied to it, which allows us to apply a single LUT to correct the whole film. For example, if the GOUT is 10 points too red, it is 10 points too red on every frame, therefore we can apply a universal correction to reduce the red by 10 points and the whole film will look better.
On the blu-ray, the colors are all over the place, so this sort of universal correction will only improve some of the shots, while making others look worse. While the whole blu-ray can be greatly improved with a single LUT (as JawsTDS proves here http://originaltrilogy.com/post/id/1042832, it would not be possible to match the colors of all the shots in a single pass).