Mayweather is said to be getting a 60 - 40 split on the purse .
Mayweather will put his undefeated record on the line in a welterweight championship unification match at the MGM Grand in Las Vegas .
Mayweather , who will put his undefeated record on the line in a welterweight championship unification match at the MGM Grand in Las Vegas , is said to be getting a 60 - 40 split on the purse .