The Larmor equation that you give neglects to include the screening constant, otherwise known as the chemical shift. This is what your 7.4 ppm represents. When you say a "200 MHz" spectrometer, that means that protons resonante somewhere around 200 Mhz, the exact frequency of which depends on the exact magnetic field, including any B0 or Z0 offset, and the chemical shift of the substance that you are observing.

Vo = gamma Bo(1-sigma)/2pi

Where sigma is essentially the chemical shift, although referenced to gamma for the bare nucleus in this case. Since bare nuclei are hard to come by, we use a scale referenced to a standard, usually TMS for protons (which I think is about 17 ppm to low frequency of the bare proton).

On a 200 MHz spectrometer from one particular vendor (Bruker), the field will typically be adjusted so that the protons of TMS resonate at exactly 200.13 MHz. This means that benzene will be 7.4 ppm or 1481 Hz higher higher (I know that seems strange, but that is just the way chemical scale is defined) in frequency, or 200.131481 MHz.

Chemical shift is a relative dimensionless parameter and as such only defines an absolute frequency when refered to the frequency of a standard.