The way it is worded is confusing, but reading it a couple times it is correct:
Fuel system: Two-barrel carburetor (V-6 and V-8); four-barrel (optional V-8); cast-iron intake manifold for all
What it is saying is the four barrel is on the optional V8 engine, which in this case is the 340, or Wildcat 375. At first read I can see how it looks like it means the four-barrel is and option on all V8 engines.
The bigger, more glaring error in the article is where it says my grandfather ordered it with a vinyl top. I don't understand why everyone always assumes the car has a vinyl top when they see the two-tone colors. This has happened more than once in writeup about the car. It has a white painted roof and came that way from the factory. Firewall tag has 'NC" on it for the paint code. N for burgundy mist, and C for Artic white painted roof.