I've been in the library (as a guest
) and it is very impressive. They have all the old blue books and other relevant publications, but I would have thought someone would have already checked for the BSCC stuff..... It may be that only way to find out is visit, and for that you may need a member to invite you as their guest. Not sure if they let 'anyone' in for research.
Not sure if period pic would queer your pitch if different wheels. Check with inspector, or if Louis reads this, he may know. I thought main idea of period proof photo was for livery / colour scheme, but that may be wide of the mark...
Good luck, and I love the car!