Should the band fit tight against all of the tabs on the backing plate? I have new cam bushings, new cams and new springs,and when centered the band is a good 1/8" off the tabs. Drum will rotate, but barely.
That is about right for new linings, you can try to shave a bit of the front ends of the linings at the cam to have a slight bevel. At times the front edge of the linings cause some interference.
Or just run in the linings tight, the drum will get warm, but should loosen up after some miles as the wear-in occurs.