Looking for better fuel milage

HHO? What is that?

Tony, the entire car is set up for drinking gas like a wino out of weekend lock up. The biggest reason your mileage is in the toliet is the cam. Second was the Holley styled carb set up richly.

IF you wanna do the power tour without the power, install a small cam. Something close to a 2bbl cam. Chrysler advertised it at something like 252* w/.410 lift. Put the 2.76 gears back in. Keep the Edel. 500, though I'd recomend the 600.

IF you have stock 1.88 valved heads, swap them on.

Since you asked here it is
HHO gas is used as the short or slang term for oxyhydrogen among the online community. Many online videos use the term HHO when demonstrating their electrolysis devices for improving car performance.
HHO gas is the product of electrolysis on H2O or pure water. Two individual hydrogen atoms and one oxygen atom. The actual chemical composition is H2 H2 O2. As each water molecule consists of two hydrogen and one oxygen atom two water molecules are required to complete the formula. The O1 from the first atom is an unstable free radical which reacts with the second oxygen atom from molecule two to form dioxygen, O2. The most common name of HHO gas is oxyhydrogen.
Electrolysis: 2 H2O → 2 H2 + O2