OK ...
Just got off the horn with KANTER.
https://www.kanter.com/i-30580646-1956-lincoln-brake-shoes.html#!year=1956||make=LINCOLN
His info source shows 12 x 2 1/2 FRT and 12 X 2 RR for a
power assist drum car.
He has the FRT SHOES in stock but does not have the rear as they order in batches and they haven't had the sell volume to re-order. He also has FRT and REAR HARDWARE KITS.
The shoes are made in TAIWAN (better than CHI-CON SLOPPY COPIES), but the quality is unknown until you try to stop. There is no exchange core charge and that is another warning (to me).
Now here is the thing, not only does the actual brake pad have to be a certain width, but the pad(s) will usually have different lengths for individual applications. This and wheel cylinder dia. gives proper brake balance on a 4-wheel drum car.
That info will be part of the BRAKE SPECS that should be in the WSM.
They are also bonded shoes which IMO is inferior to riveted linings as came from the factory.
The trick here in the US is to have your shoes relined and you will be offered a choice of lining material as to how you want the car to perform. I am sure you don't have that option.
Questionable also will be the quality of the brake drum and any hydraulic part you many need (IMO).
TO BE CONTINUED -