I would definitely adjust the cluing on a couple of the dicier crossings, but otherwise this was an exceptionally challenging puzzle in a rewarding sense!
Very challenging, thanks so much! Some of the clues were quite devilish. (I think 44A was my favorite, with 8D & 41D close behind; but there were a lot!) A few notes:
Some small errors in clues, like the double dots (17A, 23A, 41A), typo (43A).
I was not familiar with 14A or 54D; both have more familiar cluing angles IMO.
Some other clues seemed like they were kind of stretches or at least a little off (e.g., 2D, 7D).