From what I know, a 46 sized motor on 4 or 5 cell power would be a good match. More power than the old 48.
Looks like the horizontal servo operates a bay door for dropping stuff?
Motor
http://www.valuehobby.com/power-syst...g32-800kv.html
Battery
http://www.valuehobby.com/power-syst...0mah-4s-t.html
ESC
http://www.valuehobby.com/power-syst...connector.html
Buzz.