I am struggling badly with this and I too am very impressed by those who have found it quite reasonable. Hints for 20a, 26a, 10d and 22d would be welcome. And I cannot see where the definition in 1a is.
Also, I'm not sure what is meant by the displaced letter. For example, in 43a, a Q should really be a G but which can be said to be the displaced one? It depends on how you look at it, surely? And although it says these letters spell a word, I assume they have to be jumbled first.