15.0 mpg to 21.6 mpg!

7milesout.
If you want some thoughts on your other goal, ET under 14.2.

I'm running about 15.7 AFR accelerating, and 14.7 AFR cruising.
At part throttle, the 15.7 may be OK. Just to review, the engine should go leaner and leaner as the load increases (part throttle acceleration). Somewhere over 60% throttle, it will need to start going richer or it will not continue to accelerate. It may be 70%, 80% or 90% depending on the engine. By 100 % it should be in the range of 12.5-13.2 AFR.

I'm going to move the step higher on the rod so the acceleration richening comes on sooner. I'm hoping this will eliminate the 1.5 second lean spike. (1.5 seconds after pulling away from a dead stop).
Is the lean spike accompanied by a flat spot in acceleration? If there's a flat spot and the idle system has enough fuel flowing (no hesitation with gentle acceleration), then its the accelerator pump that needs adjusting.

My current setting only runs about 12.7 AFR at WOT, and I want to bring it to 12.2.
Its worth an experiment but that would be pretty rich IMO.
Have you been through Edlebrock's charts showing the effect of rod/jet combos ?
They're in the back of some of their Carb guides that are downloadable pdf