Do you want more torque for pulling power or do you want to race this truck?
GM makes a pretty good diesel engine that has more torque than the 454" cu engine. You can pull a house with the GM 6.2 or 6.5 diesels.
Now if you want to race, I know the 350 can haul ass!
Put in high performance electronic ignition, map sensor, and HP fuel injectors. That's if it's an EFI engine.
Carburetor, 4bbl, dual exhaust (No catalytic Converters) is all you need.