The drum and wheel in my photo are stock a10 63 Super Rocket and the brake is from a 68 Lightning. The Lightning shoes were a smidge wider than the stock a10 shoes, but the drum had just enough spare width to handle the difference. So the 2 ls Lightning brake fit right in without any machining, just a straight bolt-up. Maybe I was lucky with the fit.
It sure felt great the first time I pulled the 2 ls brake on, what a difference!
In fairness to the stock brake, it was worn out , glazed and covered in grease. So no brake at all, really.
Glen