Boxing-Facts and figures on Saturday's megabout

April 30 (Reuters) - Saturday's heavily anticipated welterweight showdown between undefeated American Floyd Mayweather Jr. and Filipino southpaw Manny Pacquiao at the MGM Grand Garden Arena is expected to be the richest prize fight of all time. * A fight that was more than five years in the making, the clash between Mayweather and Pacquiao is projected to generate a record $300 million or more in pay-per-view revenue, according to Forbes, with at least three million customers paying to watch the action. * Mayweather's defeat of Oscar De La Hoya in 2007 has the buy record of 2.48 million households, while his 2013 showdown with Canelo Alvarez has the revenue record of $152 million. * Mayweather is likely to earn at least $180 million from the bout while Pacquiao, a 2-1 underdog, is expected to come away with more than $120 million. * The MGM Grand in Las Vegas is expected to pack in close to 16,500 fans for the fight for a live-gate of $74 million. * Las Vegas resident Mayweather, who has a perfect 47-0 record as professional, will be fighting his 11th consecutive bout at the MGM Grand. * Kenny Bayless has been appointed as referee for the fight by the Nevada State Athletic Commission while Burt Clements, Dave Moretti and Glenn Feldman were chosen as the three judges. (Compiled by Mark Lamport-Stokes; Editing by Frank Pingue)