After seeing those 70 mm frames, I went back to the Owen/C-3PO frame, to try to get as close to the original color timing as possible. This also gives me an opportunity to share my color grading process. I don’t have an accurate reference for this shot, since the Technicolor scans have some issues for these scenes. However, I do have the uncorrected preview for reel 1, and consequently this frame for -1’s scan of the Spanish LPP, and another 70 mm reference frame of the same sequence:

70 mm frame:

LPP frame:

I use the 70 mm frame to correct the LPP frame:

Then I take the -1 frame I’m interested in:

I subsequently correct this frame with the color correction model I’ve optimized for the other frame:

Now I can match the bluray to this corrected frame:

Next, I correct the contrast, saturation, brightness, and white balance, resulting in the final color grading:

Given the process I’ve used, I believe it should be pretty accurate.