The E-3, E-6 etc. are all based on the 707 rather than the 135 series and the fuselages are 4" wider, 148" not 144".
The original Dash 80 fuselage was only 132" wide, unfortunately when Mr. Boeing went on to build the 135, 707, 727, 737 etc he kept the original Dash 80 nose section dimensions which is why it is so cramped up front.