That's where I would head. I'd try to get your cruise closer to 14:1
Maybe turn the timing up a few degrees. It may like the additional initial timing. As long as it starts OK when warm, run it. Adding timing will likely clean up your AF's too.
There's no reason you shouldn't get 15+mpg on the highway, maybe even closer to 20. That purple car got 20-21 on the highway with the 2.7-2.9 gears.