Bill McCoy is a fictional character from W.E.B. Griffith's The Corps Novels.
Was the fictional McCoy also a Marine helicopter pilot killed at DaNang? How about the "grand wizard" stuff?
If you mean "Killer" McCoy, his given name is Kenneth. And the pen name the author uses is "W.E.B. GriffiN." (W.E.B. are his real initials and he lives in Alabama, IIRC). So while the McCoy in this story is probably not real, it isn't likely that Mr Lee is just adapting the character from the novels.
d.o.l.
Criminal Number 18F