As far as I can remember the original proposed cast for Gilliams' GO included Robin Williams and Johnny Depp. Just can't figure out which one was supposed to be Azirafal and which one's Crowley
As for Death there could be only one choice of course. Christopher Lee and no one else.
And if we're talking about Gilliams' ability let me just remind The Fisher King...
There's one thing I really can't understand. It's the whole 'the film would spoil it for me' approach. Well, there's a very simple solution to this problem - for crying out loud - do not watch!
If the film existed you can still opt out from watching while as long as it doesn't exist I can't opt for watching. It's not so difficult to figure out which situation would leave more people happy :>