dnd 5e – How to convert "EPIC" 4E Only monsters to 5E?

I have been browsing the web to find a good example of conversion of EPIC D & D 4E monsters (level 20-35 + in 4E) to equivalent 5E versions. I've seen a couple of threads here and they help me do it conceptually, but I'd love to see a basic statistics conversion / save / AC / HP / CR (for example) … Orcus or some deity, etc.

I checked the blog post of the Improved Monsters Statistics and the table that it resolved seems good. I also know that I could look for an equivalent CR creature in the 5E MM / Volos / Foes books and build from that, grafting the 4E powers that I like in simulations 5E. That is all good.

But I'm stuck on this: How are creature levels 4E to 5E of 1-35 + assigned? More specifically, what is the 5E CR / Level of a 4E creature of level 35, or even a 4E creature of level 20 for that matter?

Looking for good and coherent ideas to move some favorites from 4E to 5E.

Thanks in advance for the help!