What I like about AFB's and Edelbrock's, is the metering rods are easily changed, and readily available. You can set them easily for mileage, and keep the slightly richer set to swap in for a weekend of fun and games. It takes some monkeying around to sort them out, but it can make a few mpg difference.
Keep in mind that it's the second, fatter part of the rod that determines cruise mixture, and that weaker plunger springs delay the richening action.