Back in the day, we used to ARC the shoes to fit the drum diameter. (fancy AAmco machine to sand the shoes down). you may need to use different brand shoes or have someone ARC yours.
Do not let them get hot, or you will need new drums as well.
Re- reading your post, if you didnt turm the drum, two things can be wrong, one is a rust ridge on the outer edge...sand or file off the rust completely.
the other thing, sometimes the drums are not machined all the way to the corner and the shoes bind when they are installed.