Two different ways to look at it:

1) That inflation-adjusted value, which is about 2300-2400 dollars, is using the infamously-managed consumer price index. Using other realistic inflation measures, it's higher.

2) Gold went from $35 to 887.50 in that bull market, a factor of 25. We started at $252 in this run; $252 times 25 = $6300.