Will not rev above 2K

["Mark Dent" <mark@dealermats.com>]

Ok here goes:

1964 1500

This car will start and idle, and run fine, but will not rev above 2000 RPM.
New gas tank, new fuel filter, I have tried 2 fuel pumps, and 2 different sets
of carbs.  I can blow back to the gas tank, so I know the line is not clogged.
Plenty of fuel is going through the filter.  What else can it be?

Mark
Phoenix MD