Yours could be from a kit, or something, but it could work.
I went with a Raybestos MC 36406 (15/16" bore) after not liking a MC36412 with a 1-1/8" bore. The MC36406 works much better. It's easier to push, but does travel a bit lower. I also went with an adjustable push rod.
I looked around and a lot places are out of stock, but Summit substitutes this one.
Dorman M80266 Dorman Brake Master Cylinders | Summit Racing
