could it be another name for Buk Sing CLF? Tarm Sam opened up in Siu Buk (Pak)and called his sshool Siu Buk Hung Sing Gwoon, which they shortened to Buk Sing.
I've seen many variations of the name, so that might be a possibility/ It may be an offshoot, or a school separating itself for political reasons, just as some Uechiryu schools call themselves Pangainoon, Kenpo schools calling themselves Chuan-Fa, Hung-Ga schools calling ourselves Siu Lum Hung Kuen. (oh, did I just say that?:-)
Just guessing.
"My Gung-Fu may not be Your Gung-Fu.
Gwok-Si, Gwok-Faht"
"I will not be part of the generation
that killed Kung-Fu."
....step.