It is based on the Gale 12D16 circa 1957 Similar to the E/J 15 but
smaller bore and no roller bearings. 2 1/4" bore compared to the EJ 2 3/8".
Don't know if the E/J 15 head gasket will fit but for the bore.
You can buy head gasket material and make your own gasket.
Over at www.aomci.org they may be able to be more specific.