Doesn't have to be that particular bit but those makes come in a 6 1/4.

http://www.thehorsebitshop.co.uk/search.php?xSearch=6+1%2F4

Not sure if that link will work and bring up the search i did.

According to someone on another forum this company will make bits to size.

http://ridingbitz.com/

Hope that helps.

Horses stay the same from the day they are born until the day they die... They are only changed by the way people treat them'. Tom Smith - trainer of Seabiscuit