Even GM cannot give you a definitive answer, because they did not keep those records. You can start to narrow it down by options like Richard has suggested. Maybe a better question is "How many 67 SS/RS L35s are in the CRG database?" It will take someone from the actual CRG to answer that...
I have found it is better to break your larger question down into several smaller questions on any research site. Generally, you find the answer through several answers. Good luck, and welcome!

BTW, sounds like a great car! Share more infromation about it and keep us posted on your restoration. We love pictures and details!