Previous record belonged to an Indian and I wasn't even aware.
Not sure about that... these records are all very vague. For example, the following link lists a guy having made 403. And this was a while back so there must've been a higher score sometime.
http://www.thehindu.com/2005/07/30/stories/2005073007702100.htm
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Incredible 403 in 137 balls
Karachi: Hitting quadruple hundreds in cricket is a rarity, but hitting 403 in 137 balls in 36 overs is surely an exceptionally rare feat.
Pakistani batsman Shahzad Malik, while playing for the Langleybury Cricket Club in Hertfordshire county, England, hammered 403 runs in just 137 balls, 38 of which went for six. He achieved his feat against the Middlesex Tamils, reports The News.
The sport.telegraph website quoted Langleybury's captain Nigel Ilott as saying that "the Tamils were reasonable club cricketers, but they had a lot of spinners and Shahzad loved that. It was as if someone like Kevin Pietersen had come down to play at our level."
The report said that Shahzad has already represented Pakistan A, and is fast emerging as an upcoming batting talent in the domestic cricket circuit.
In the 2004-05 season, in first-class cricket, he hit 1,008 runs at an average of 72 with the help of four hundreds and five half-centuries, it added. — ANI