The #16 wire mentioned is just the numbering system for the wiring diagram, not indicating the wire size. It appears to be permanently part of the fuse panel. The Jegs information does not show the wire sizes and hopefully they are sized correctly.
Fred, that wiring diagram for the "motor group wiring" that Jegs shows on the website has some errors. The alternator and the ignition resistor are not shown correctly. If you are using points ignition the wire labeled "not normally used" should go to the opposite end of the ignition resistor. The alternator wiring is shown correctly on the next page of the online instructions. Be sure that you wire them correctly and not as shown on that diagram.