The $180 question...
Do you absolutely need a dust shield/backing plate for the parking brake shoes to work? It seems the PO drilled the rivets out for the shield (guessing they didn't need a parking brake), so there is no place for the hold-down springs and pins to mount. This means the shoes will "float" inside the drum instead sliding against the flat backing plate.
$180 question because I might buy new from East Coast Gear. I don't have time/too lazy to go to a junkyard at this point.