I know you don't want to hear this, but in the first place your tubing headers(how did I know?)are the greatest source of unnecessary heat.OK thats said.
Increase the airflow through with larger airmover.
Cool the necessary heat contributors with a cooler running engine (thermostat).
Move the A/C condenser so it doesn't contribute.
Airflow through the engine compartment should be in at the front and out downward over the engine/exhaust system.
Wrap or coat heat emitters with insulation(unless they are the cooling system)
I understand your hesitancy to make some compromises because they don't look "cool" but be challenged to work with these as you can until you're satisfied.
Remember there is no reason the 400 can't be made to run just as cool under the hood as the original 6 pack doing the same work.
It takes x horsepower and fuel to move it down the road at a given speed/load regardless of the engine.In fact the more efficient modern engine SHOULD reject LESS heat to the exterior.
Ok time to hear from others.
