It appears I am slightly late responding to this question, my apologies. :-)
The date in the Construction Record is really misleading. It was originally "May 28/34" in ink. Someone then changed the 4 to a 1, making it a 1931 (and did so for all numbers from #1206 to #1211, i.e. the entire #1206 class of 12 1/2s). However, itis clear that the correct year for the entire class should be 1934.
As per the Construction Record the work order to build the #1206 class had indeed been issued 'Sept 8/31. But as per the contract for #1207s in the collection of the Herreshoff Marine Museum it was contracted for on the '30th day of June 1934' for a delivery 'on or about July 8, 1934'. This boat was thus built on speculation and could not be sold until two-and-a-half years later. The contract was signed by Stephen J. Watts, a boatbuilder in Marion, Mass.