The Floscan 201 transducer should be "to spec", or nothing. The "pulses per USG" is engraved on the side; e.g. 298 means 29800 pulses per USG. This is for avgas. There is no reason why one should get a different figure unless there is something seriously wrong with it and then there will probably be no output at all.
There is no "calibration" whatever on the transducer. The calibration is in the displaying instrument, but in any decent installation just setting "29800" (or whatever the engraved figure is) in there should give you good accuracy; within 1-2%.
Floscan sell them for about $100 to Shadin who sell them for over $600 with an 8130-3, and claim to test each one on an avgas flow test fixture.
The exception to the foregoing is where there is flow turbulence or interference on wiring, as described in one of the articles linked earlier. This can give varyingly weird results, and many people, and aircraft dealers too, have (in ignorance) tried to compensate for that by setting a fudged K-factor.