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There is no 1:1 conversion between the two. That being said, let's get to the question behind the question, and perhaps we can work outside of the box.
Are you looking for a DL award that requires 80,000 miles? Are you looking for 2 DL awards?
Keep in mind that soon (unlesss I am mistaken) you will be able to use US miles for UA flights. You can also use DL miles for domestic UA free tickets. So some combination without conversion might work here.