That adjuster is the key. it's a royal pain to turn, plus you have to get the spring loaded auto-adjuster out of the way. It's almost impossible to see, you are in an awkward position, and the movements are subtle, plus it's difficult to know if you are really turning the star wheel. Be very patient, and listen for noises that indicate you have contacted and moved things inside the drum. After you think you have enough turns on the star wheel, turn about 25 more times. Then try to pull the drum off while turning the bottom of the drum towards the rear of the car. If it moves away from the backing plate but doesn't come free, wiggle a bit, but if that doesn't get you anywhere, put it back and put some more turns on the star wheel.
My 5th Ave rears took what seemed like 150 turns (albeit at about 1/5 of a turn at a time), and had a ridge about 5/16-3/8 on the drum. YIKES. ...and that's "only" a 25 year old car. The 66 was actually MUCH easier. I also learned that the 7 1/4 brake shoes will work on the 8 3/4 if you use the E brake finger from the 7 1/4.