I did some more cross referencing, and found some more part numbers:
14"x2.5" Front Brake Shoes - $65 for a set for 4
Normal - Raybestos 109RR
Premium - Raybestos 109PG
I guess there was also an option for larger 15x3 brakes. I do not have these on my C50.
15"x3" Front Brake Shoes
Normal - Raybestos 134PG
Premium - Raybestos 134RR
Still no luck on the rear shoes, but luckily my rear shoes are still in good shape.
Worst case, I could probably reline them myself like I did with the parking brake, but I am not sure I trust my own work that much... yet.
No information on front or rear drums yet, but they are pretty beefy and should be able to be machined again if needed.