Hello Fitz,
Is this the next project? There is to my knowledge no documentation verifying that the Chestnut serial number was anything but a simple work order number or that anything can be deciphered from it.
Most Chestnuts are not marked with a serial number at all. Those that are, might have “a five digit number, or a two digit number followed by a four or five digit number, or a letter C followed by a five digit number. One can actually find Chestnuts built during the 1960's with all of the above mentioned number sequences.
Cheers
Dick Persson
Headwater Wooden Boat Shop