I think you would be better off getting in touch with markcycle from here on ES he
has developed and sells motorcycle class hub motors i saw them listed on ebay for ~$950
they are ALOT LOT more powerful than the one you have linked to also and highly likely ALOT better quality
You can get a complete adult size (3000 watt 60 volt 50amp lead acid) for $2400.00 from (R MARTIN BIKES.COM) or a ( 3500LI EXTREAM SCOOTER) FROM (ADVANCED ELECTRIC SCOOTERS.COM) for $2000.00 free shiping with 60 volt 40 amp lithium battries.