Chevy called their FI system "ramjet" in some of their literature, I guess referring to the pulsed ram effect, tuned runners, like a tunnel ram has.
I couldn't find a cut through diagram of a '63-'65 FI unit, but it is basically the same as the first series unit, with individual runners leading up to the plenum, but now the plenum has a removable top, instead of a sealed cast top.
here are some detailed outside pictures that you can tell it is of the same basic design, like an enclosed tunnel ram.
http://www.cranescorvette.com/f_i_-2.htm
Where as the weber carbs are open to the atmosphere (plenum), the corvette FI system runners are open to the plenum, which is like atmosphere at WOT, basically the same effect.