There is a documentary coming out about this in the near future...
This dude fanatically has tried to get the original version released before it got butchered by the studios but I am keeping an eye out for this documentary and also one day we get to see the now disowned film that Michael Mann made that was visually compelling and a strange curiosity of what might have been.
The person doing the documentary has a website all about the film and has also made a molascar Manakin if you like as he is involved in creature and make up effects and was one of his many inspirations to get into this line of work.
Practically there is a much longer version at about 4 hours long... Which is probably a workprint but that could easily be 3 hours after editing.
Documentary title
CHRONICLES OF A WWII FAIRY TALE: THE MAKING OF MICHAEL MANN'S THE KEEP (2013)