Lil Brutto said:
kk650, I'm happy to break it down for you but it depends on what cut you wish to use for your project. US/International, Italian or English Extended? This info will make it easier to advise on what audio/video sources will be required.
I don't think the goal should be to recreate the colours of Mondo; rather the focus, as you said, should be on removing the blanket yellow and optimizing image dynamics so that it looks...good. The regrade settings you used for your screenshots are already a big step in the right direction.
On page 1 of this thread is a description of my project that I posted on the Sergio Leone Web Board in late 2013. I put my project on hold until the release of the 4K BD. If you're intending to recreate the International cut, then this should help clarify things.
Your project sounds like exactly what I've been waiting for them to release officially