Edelbrock has a tuning guide that shows the combinations of jet and metering rod you need to make the carb leaner or richer. Take what Royce said to heart: get the timing and ignition right first. Then adjust the idle air screws, then you can start changing the rods and jets. My experience with Edelbrock is that they are set up for a Chevy 350 out of the box and too rich for the stock 289 or 302. Chevy runs a different strategy for vacuum advance than Ford and it makes a difference because the carb is a mechanical computer that uses vacuum as its primary input.
What I do is to follow the chart to replace the jets and or rods to lean the carb out. What you are looking for is lean surge when cruising at about 45 mph on level ground. Lean surge feels like a temporary loss of power sort of like hitting a head wind. Once you have that dialed in you know the lean limit. Typically I go to 2 steps richer and drivability and economy are both good.