John (carbking) is spot on. The head and intake ports cannot be made to flow well enough to support a lot of increase in HP or torque. Lots have tried, myself included, but the limitations inherent in the design of the motor prevents any real drastic improvements. That being said, a lot of things can be done to improve that situation, understanding that these are modest improvements. In addition, you have to ask yourself what you intend to do with your truck and the motor in your truck. If you are just toying around the neighborhood, then the stock set up is probably right. If you like to tinker, then you might want to fool around with dual carbs or a single carb of some other design. If you like to put your foot into it, then you will go to some other extremes. I tend to have my foot in the gas pedal so I like to really mess with the motor and I really really like the look of multiple carbs on these motors so I have almost always had them on my motors. I also like to dress them up and tinker with vintage speed equipment. Its just what I like. You should tinker with what you like. Life is short. If you want to tinker with the Clifford intake, you should. There will come a time when you can't. Frankly, when that day comes, and it will, the dollars you spent to tinker and enjoy the hobby will not mean a darn thing.
This is one of my motors, a 261. I have built similar motors for cars and trucks for over 40 years. I love it. Its all in what you like and so let your gut guide you and go have fun.
