Those look like a aftermarket or homemade version of the 64-66 A body V-8 mounts.
Actually that's a lot like what mine look like. I'm at work but can get pics later. The plates look very simple - just like that.
When we were over at dads today I looked at the rubber isolator mounts that go between the brackets and the K frame. They appear to be the thin (just over 1" thick) ones. So this combo just might mount the 318 in the car properly, but the brackets look to tall to me. We will see when we test fit the drive train. Eric L