Here in the US its the land of prolific litigants and their lawyers. So, this can be challenging to find someone to do this. I have a local guy who runs a machine and fab shop who is also passionate about motorcycles but he is the exception to the rule. Most places as soon as you say "Motorcycle" they cant get off the phone or away from you fast enough.
Depends on the brake hub assy as some distort more than others and Ally hub with cast liner or cast iron hub entirely? or a bolt up arrangement can differ.. But it IS worth doing as it does make a huge improvement. Down in California is a shop called Vintage Brake and they reline and will skim and can transform a old bikes brakes, but for me, shipping a complete assy is very expensive,
See:
http://www.vintagebrake.com/ But perhaps some good info can be learned from them.
I know a local guy, "Panhead Jeff" who in his day job is an engineer and while his interests are primarily American bikes he played around with upgrading early HD and Indian brakes and got really impressive results, as Radar said about his Indian Scout "I can skid both wheels now and it never did that before"
So, because of the aforementioned aversion to liability, Jeff could not find anyone who would reline old shoes with some of the modern materials so he bought a variety of high tech brake materials in bulk and relined them himself. He found some carbon fibre or other high zoot materials that worked really well.
I tried some of his bikes and was really impressed with the results, He skimmed the drums, optimized the actuation, and with the modern materials transformed the braking.
As he pointed out, A drum brake has more theoretical contact area than any disc brake so its a question of getting it working right and dealing with the heat issues. Most vintage bikes I serviced when my shop was active were using about 25% of their contact pad due to poor fitment, installation and poor bedding in. Probably the biggest misunderstood drum brake out there is the Conical brakes/hubs fitted to 1971-73 Triumphs and BSA. (They actually work quite well when properly adjusted) They dont deserve their moniker of "Comical brakes"