Not knowing what the cam and/or compression is handicaps you a little.
That being said I would want to know what kind of ignition setup you are running and how soon does your advance come in?

I would think a compression test would help to know your cylinder pressure and help with a new cam designed to give more low end.

Not a fan of the eddy 750 but tune what you have first.

Heads would make a big gain but you may get it with some tuning and a cam.

The only other intake that may work is the edelbrock ch4b(shorter than the performer),better for mid range and top end.The stock hp intake probably beats it down low.
The Holley street dominator may work but likely to tall for the air grabber.