Drum brake installation troubles...

The only problem is I had the machine shop throw away the old rears after they said they didn't have enough material to be turned... as for the front the fit works well with the old drums

That could point to the e brake adjustment. Have you recently upgraded to 8 3/4 from 7 1/4? If so that is the problem. Try and back off the e brake adjustment and see if that helps, it doesn't take much.