We've seen a copy of a letter issued to producers Scott Jay Kaplan, Emmet McDermott and author Christina Binkley after the industry vets optioned the rights to CB's book, 'Winner Takes All' -- which details Steve's rise and fall as a casino bigwig -- for a dramatic retelling.

The letter was sent from powerhouse attorney Patricia L. Glaser on behalf of Steve ... and it makes clear that the Sin City businessman won't tolerate creative liberties taken in any big or small dramatization of his life -- including what Kaplan and McDermott are working on.

The billionaire's legal team explicitly expressed their concern for the project ... citing what they allege is the author's "history of false statements and mischaracterizations regarding [Steve]" -- referencing the source material that'll serve as the inspiration for this project of theirs.

While Steve didn't threaten to put the kibosh on the movie here in this letter his attorney fired off -- not that he had any real right to stall the project -- he does demand, via Glaser, that Scott and Emmet verify every fact presented in the story and ensure that their sources are fully vetted. Translation ... no stone should be left unturned when it comes to research!

And it's pretty obvious that Steve means business here -- as the letter threatened legal action over any falsehoods that may be presented.

Even though it's clear that Steve has never been a fan of his depiction in 'Winner Takes All' ...  it doesn't appear he ever sued over the book in the 16 years since it's been published.

The book found itself on the NYT Best Seller List after chronicling the meteoric rise of Wynn -- who was forced to step down from Wynn Resorts amid sexual misconduct allegations ... claims he's denied, for which he's never been charged with a crime.