How And Why Move Emulsion Jets?

The introduction of air into the main well affects the fuel curve to put it simply.

Why do it? To tailor the fuel curve to the engines requirements.

What are the benefits? A better running engine as the AFR is correct for what the engine wants and where.

How is it accomplished? Depends on the main well design but in your case if you're using a Holley four barrel you could buy some metering blocks and try changing their locations to see how that affected engine performance. That said I have it from a very knowledgeable person that if the Holley is correctly sized for the power output of the engine then the standard Holley size and placement (emulsion) is correct.

They used to sell these:

Rapid Tune-Up Tricks For Your Favorite Holley Carb

Once you get past the big HP increases they got from going from a stock 650 DP to a HP main body at the bottom they show what are tubular emulsion set ups that one can drill any and as many holes as one would like.

Just look at a Carter Booster and see how they introduced air into the main well.

This is a very simple introduction.