Another option may be to acquire the leather for the seats, and dye the door cards and arm rests to match. I have had good experience with a couple of different dyes from Colorplus. https://colorplus.com/
In this picture, I had completed the front seats, rear armrests, and the armrests on the doors. The door cards had not yet been done. These were my original rear seats; at this point in the process I was having the leather that matched the front seats mounted on another set of rear seats. I actually showed my car at the Pittsburgh Vintage Grand Prix like this.
I post this picture because it may provide another option. I almost did not change the door cards, and this picture gives you an idea of what your car might look like if you don't. I would recommend doing all the arm rests, including those on the doors, to match the seat leather.
In this picture, I had completed the front seats, rear armrests, and the armrests on the doors. The door cards had not yet been done. These were my original rear seats; at this point in the process I was having the leather that matched the front seats mounted on another set of rear seats. I actually showed my car at the Pittsburgh Vintage Grand Prix like this.
I post this picture because it may provide another option. I almost did not change the door cards, and this picture gives you an idea of what your car might look like if you don't. I would recommend doing all the arm rests, including those on the doors, to match the seat leather.