When you say you could go a little leaner, do you mean at idle or cruise speed ? Is that a stock motor or does it have a non factory camshaft ?
Assuming it's a pretty stock motor with plenty of vacuum, I do run leaner than that at idle myself and also a bit leaner at cruise as well. It's easier to changer the cruise AF with the later APT carbs like I run, but if I were you, here's what I would do, but that is just me. I would slightly enlarge the upper idle air bleed which is most likely on the air horn on your carb. That would lean out the idle and also have a small influence on the cruise AFR as well, but much more on the idle which I think you could lean out more.
Frank.