These two compilations unearth obscure yet stellar ’70s party music. Cult Cargo spotlights musicians from Freeport, Bahamas, who recycle American rhythm-and-blues riffs with freewheeling vigor. Sylvia Hall’s “Don’t Touch That Thing” locks into a rubbery New Orleans groove, and Jay Mitchell’s 12-minute version of “Mustang Sally” will exhaust even the hardiest dancers. The Cuban artists on Si, Para Usted are more urbane but just as spirited. Los Tainos’ “Amor Mio” echoes the big-band soul of Earth, Wind and Fire; Los 5-U-4 recalls Funkadelic’s twisted psychedelic jams on “Baila, Ven Y Baila.”