The drum is getting constantly polished by the shoes, so mooth and shiney is OK. Are they adjusted properly? How old is the bike (assuming these are original)? How many miles? Is the wear indicator within range? Are there any grooves or cracks in the drum?
Is the drum within manual specified thickness parameters? If not, replace it. The specs for the drum are on manual page "CHASSIS 5-32"
IMHO, I'd say it's probably cheaper to buy a good used rear wheel w/ drum than to replace it and re-lace the rear wheel.
