New bb build fuel economy

I have a 440 in my Duster that gets around 16mpg (if I can resist the urge to floor it).
30 over forged pistons,
Shaved 452 iron heads,
11:1 compression, (minimum of 93 octane required)
Edlebrock performer rpm intake,
mild street/strip cam,
Schumacher headers/2.5” exhaust/cheap 16” summit mufflers that barely muffle,
Holley Sniper efi and ignition system,
T56 magnum with a .63:1 overdrive,
3.73 rear end gear.
I didn’t build this car for fuel economy, so I’m sure it could be improved significantly with some aluminum heads, and a cam with less overlap.