Put a center punch mark as close to the center of the rivets as possible, then set the hub/drum assembly up in a drill press and drill the head off the rivet with a large drill bit, 3/8" or larger. The drum should be able to be removed from the hub once the heads of the rivets are gone by tapping with a big hammer between the lug studs to shock it loose. Once the drum is off, either punch the remains of the rivets out, drill them out, or just grind them off flush with the hub. You really don't need to rivet or bolt a replacement drum on, the wheel will hold it in place OK.
Jerry
