Are you doing this just for personal satisfaction?
The trouble with adapting for screen is that differences from the source text are inevitable. Look at 'Never Let Me Go' which Alex Garland adapted from Kazuo Ishiguro's novel (one of my favourite books). It was overly dedicated to the text and as a result has bombed both critically and commercially. What works on the page and what works on the screen are two very different things.
So my recommendation would be to not be slavish with your adaptation. Sure, some films to take too great a liberty with their source material, but with any adaptation there should be a level of compromise.