Since the ECU runs in closed loop, there's not much you can do to the fueling to improve fuel economy. In any case, I'm not sure how much leaner than 14.7:1 you can run before the pistons get too hot.
You can optimize ignition and cam angle settings, which will help economy. I think the only way to do this is on a dyno, and tune the area from 2000-4000 rpm, 30-60 kPa for lowest manifold vacuum with a constant load. From what I've seen the dynojet constant load setting is too course to work.