Large chunks of cast iron are not usually hard to find, they are just hard to get rid of when you don't want them. Of course they usually need reshaping, which can be a slow and arduous process if you have to use a hacksaw by hand. My usual approach to such things is to find something that is a bit bigger, and remove the surplus. In this case it looks as if it has a couple of tapped holes in its underside, for attaching bolts. The handle on the top may be useful for lifting the front of the machine, to make it easy to drag it around the property.
