Not really sure. If it helps, the '69 parts book lists the part numbers by brake diameter, not by brake width or differential size. They have different part numbers between 9", 10", and 11" applications.
Exactly right. The emergency brake hardware is based entirely on the diameter of the brakes. If you have 10" brakes on both rear axles all of the e-brake hardware should swap right over. The width of the brake pads doesn't matter, neither does BBP or SBP as long as you're just talking about the e-brake hardware. Or any of the self adjuster hardware for that matter.
