Although I mostly agree with Mr Hotrod, I don't believe head work is necessary to run a dual carb setup. you may clean it up a little bit, but porting, polishing and oversize valves are a wasted effort on these engines for a street machine. True it might help in a race engine, but the head work will reduce the intake velocity at low speeds, reducing torque. You would have to spin the engine faster than 4500 rpm to get the increase in hp from the flow work. If we are talking about a chevy 235/ 261, or gmc 270/302, 5000 rpm should be considered a red line. If we are talking about the later 250/292, these motors can be spun significantly faster and could benefit from the headwork suggested.
As a point of refference I am running 5 2bbls on my 302 gmc. I haven't had the engine running in the vehicle yet, but I have had it running on a stand. It looks and sounds wicked. But yes, the 5 carbs are more for eye candy then they are for performance.
