Upgraded my son's bh6 300a@450 to a retail celeron1000/slotket over the weekend. Had to flash the bios, added an addl 128 megs of memory. Definitely a big improvement. Less than $100 delivered form Augustustech. Their generic slotket allows for fsb adjustments, not voltage, which shouldn't be an issue with a be6.
Should be about the same for your board- fcpga processors up to 1100 are supported by the latest bioses. Might be able to use a tualatin on a special powerleap slotket, probably not worth the $$.
The new lever clip on the retail celeron gave me some trouble, snapped the mounting tab right off of the slotket. YMMV, but be careful of the evil clip....