Like some unholy cross between Wes Montgomery, Sly Stone, and George Clinton, Johnny “Guitar” Watson’s distinctive musical recipe in 1978 produced Giant, an idiosyncratic funk classic. This was an era in which many aging R&B stars were being subsumed by the disco trend, but Watson, being the larger-than-life personality he was, reformed disco in his own image. Shadowy yet effervescent, “Miss Frisco (Queen of Disco),” “Guitar Disco,” and “Tu Jours Amour” have the rough edges of music created in a cellar, though Watson plays to the hilt his role as supreme pimp and ringmaster. There are few people in the R&B world for whom music seemed to come so easily. Whether scatting or using the newfangled technology of the talkbox, Watson’s improvisatory spirit turns quirky workouts like “Base Station One” and “Wrapped in Black Mink” into instrumental classics. Watson was never more effective than when he turned down the volume to make a unique form of hushed funk; see “You Can Stay but the Noise Must Go” and “Baby Face (She Said Do Do Do Do).” But the standout here is “Gangster of Love,” a pimped-out update of Watson’s signature blues tune from the '50s.