I'm with tincup. Carbs suck. They are a giant restriction on the intake. Put a 1000 CFM throttle body on that motor and add port injection and that would be a 500HP motor.
Back when the Hemi's first came out Hot Rod got 481 HP (At the flywheel) out of a stock 5.7 Hemi with a Comp Cams XFI 273, TTI Headers, and a tune.
If you don't make 500 HP with a Hemi you're just not trying very hard.
Regards,
Joe Dokes