As there are a few different 6200s of this brand, a pic of the card would be helpful. Problem is that not all 6200s run with the same ROM. The XFX does. But most others need something "taylor made" for them.
By the way: BfG isn't the fastest you can get. There is a particular one of Club3D which has RAM labeled 400Mhz. This one can be reliably run at 430/450(!)Mhz, resulting in nearly double the speed of one of the standard 350/266Mhz-cards.
I once made
a thread for that in german cube user forum, including benchmarks.
This one should be by far the fastest card that - unlike monsters like the Rad 9700/9800 or the GeForce 6800XT - can be run in the originale cube case (which finally makes a cube THE cube imho) and the stock VRM.
They are on ebay from time to time and look somehow like
that. But most important is the labeling of the RAM chips, wich has to read 400Mhz.