Academic work, proofread on overleaf, 60 K words

I am at the end of my dissertation in English. So far, I have 50 thousand words and expect to reach up to 60 thousand+. I want to ask 1) if you would be available to work next week, 2) if you can do the work on the overleaf, and 3) how long this revision would take (from your experience): a "guesstimate" is good enough.