I've done exactly the same thing when adapting screenplays for convential narrative. If you want an example of how present tense can be done and done well, check out any of John Rickards' books. It seems a bit weird and gimmicky to begin with, but it reads fine once you get into it. What is weird is actually writing the book long hand. I write lots of notes that way, but writing the actual book without going via a keyboard? Surely you have a gizmo that saves you having to do that?