Huck type brake drums are expensive. I don't know for certain but the "wavy" part you are looking at is just to conform to the drum. Yours looks to be held in place by the Lug bolts(press fit on the studs?) Might need to press them out 1 at a time to release the old drum. I haven't pulled a Huck front drum from the hub in a very long time, so not much more I can add. The replacement drums are close to 150.00 each. Might try getting it turned and see how far you can safely go. That groove won't hurt much, it will make very little difference to the brake shoe. But it will make pulling the drum after a bit more of a challenge. The real reason(opinion I know) for turning the drum is to keep it round. A nice flat surface for the shoe is nice, but not mandatory. A round surface is.
