Hey Jason,
According to what I've read, the 1405 is a "preformance" carb whereas the 1406 is an "economy" carb. So it makes sense to use the 1405 guidelines.
On that note, Edelbrock cards are generally peticular when it comes to evelation..... The higher up, the leaner they like it. And vise versa.
I'm using a 1405 with the Edelbrock "Preformer" package (intake & cam) Proform aluminum heads, headers, and H.E.I. as well.
It was set up for the Great Lakes area, so when I got it up here to the Rockies I had to lean out the jets to get it to run right. It took a couple swings to get it right, having first leaning out the rods to far and getting the stumble your talking about, I went back to the original rods and took the jets down two steps.
Presently I'm getting about 23 miles/ gallon (Can) with a 200R4 transmission, and the overpowering smell of wasted gas is gone, as well as the stumble.
Still has just a gentle hint of the scent.