Do Not remove the slotted screws!!
The drum is not retained by them
the reverse of the threads on the slotted screws is deliberately peened to make sure you cannot remove them. You will destroy the threads in the hub if you get them moving.
Remove the 4 hex 7/16 AF bolts then strike the drum hard on the wheel face with a copper or hide mallet, whilst pulling the drum lip back towards you. This will normally shock any corrosion loose and also jump the drum over any lip caused by the brake shoes. Repeat as necessary pulling on different parts of the circumference of the drum
Mine came off easily so good luck.
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