Hi !
You're lucky because the plain snowflake wheel is not available new.
Replacing the drum brake surface is not easy nor cheap. And is far from warranted.
First you have to find someone with a lathe big enough to hold the entire wheel.
Then he will have to remove quite all of the old drum brake, then he has to machine a tube with the proper dimensions and install it in the wheel with liquid nitrogen on the tube and heat on the wheel.
Once all is cooled off, machine the tube, now hopefully firmly held in the wheel to make it round...
If you find someone willing to do so for less than a new wheel, give me his credentials ;-)