If it's running Ok why mess with it? If it's NOT running OK, what's ailing it, specifically?
To answer your question, I've done a bunch of these, and generally end up at 2.5 or so. I can share that there is no upside trying to get as lean a setting as possible. All you're doing is making it picky to start with a terrible cold idle that often stalls. I would WAY rather have it set on the rich side, for easy starts and a minimum amount of trouble during warm up. Don't worry about fouling plugs with a rich setting. That's just not going to happen...