The NA Miata one might work. The only difference is the cut-out for the thermostat housing, which is on the back of the block on the Capri. You could probably cut a square of plastic out of something, and use a soldering iron or similar to "plastic weld" it to the cover. Just an idea.
Mine are pretty trashed as well, and I spent hours looking for a replacement. Good luck. You'll either have to run without them (which is fine to be honest), or get creative with what you have.