I always thought that the brake discs were one of the few Morgan-specific parts. Can you not get your existing discs refaced?
TBH I'd be surprised if they were worn beyond their service limit in only 12 years, Morgans tend to do pretty low mileages and tend to wear their brakes very lightly. I replaced my 4/4's discs at 83k miles, but that was mainly because I was upgrading the brakes anyway.
