ISO Kelsey Hayes Caliper

They are still available type in a search on Google. They are also the same caliper as a 64-66 mustang.
Hey oldman, I think that although they are essentially the same the ford version has a different position and thread on the intake for the hydralic hose. I think people have used them but adapt the hose fitting so use different hoses altogether.

For the OP. I have a couple of original cores in Alberta, or Rock auto does sell new ones and they do deliver to Canada for reasonable $