The former St Pat’s man struck in either half as the visitors claimed a somewhat flattering win.
Pat Scully’s side started the game brightly and Sheppard and Ian Maher went close before Sheppard opened the scoring after 20 minutes, racing onto Ray Scully’s through ball and slotting past a helpless Gallagher.
The visitors were always dangerous on the break and on 63 minutes Sheppard wrapped up the game when he got on the end of Willie Doyle’s cross to poke the ball through Gallagher’s legs.
Gallagher; Hudson, Griffin (Skelly, 60), S Kelly, B Kelly; Hoey (Kierans, half-time), Dunne (Vaughan, 83), Finn, Marney; Hughes, Hynes.
Murphy; O’Brien, Price, Kenny, Clarke; Duffy, Scully, Maher, Shields; Sheppard (Long, 72), Doyle.
Colin Fitzgerald (Dublin).