318 2bbl Intake Mods ?

I had a 69 D100 with the NP435 trans and 3.91 gears all stock, I added a set of headers and that was the best running 318 I have ever owned, totally stock, minus the headers, it was really strong. And I have owned alot of 318's.
The only thing I could find was different, from all the other 318's was that factory single plane cast intake.
Sounds like it was a fun truck !! I am about to start down the road for my "gas mileage & performance" Van project as I prepare for NNN. Sticking to my word on just working with the factory equipment. My job is just to allow the components to preform at their premium. It's going to be a blast for me, as I am so much attracted to this type of project.