I just checked with my neighbor, who owns a nice SNJ and measured the
diameter.

His prop is 108 inches (9 feet) long. He tells me that the prop can be
shortened 20 inches and still be legal, so the correct length for the
T6/SNJ prop is anywhere from 88 inches (7 ft 4 in) to 108 inches (9
feet).

I hope that this ill clarify the issue for the gentleman inquiring for
his scale model.