I managed to pick up a BSB clock bracket off of ebay. These have been used around 2009 to 2016 for teams such as Swan Honda to the Honda Racing BSB Team. They were made by evotech and dificult to source. At the bottom is a photo of the bracket used on Jenny Tinmouths BSB bike. I spoke to Evotech who explained it was designed to be interchangable in the event of crashes and changed to fit later speedos.