Nyree,
thank you for supplying the HTML and JCL files to test on.
The HTML file generates an error message from the HotPot module:
- could not insert submission form
Hint: you can see this error message if you set Moodle debugging (Site administration -> Development -> Debugging) to DEVELOPER level 
In order to get your HTML file to be accepted by the HotPot module, you need to re-instate the following tags just before the closing body tag, </body>
<!-- BeginSubmissionForm -->
<!-- EndSubmissionForm -->
These tags were in the original Find-It (a) templates, but somehow they have been removed during the creation of your HTML file. If you put them back in, the file will display as expected in the HotPot module (see attached screenshot)
You can also add this activity to Moodle by using the JCL file as the source file for a HotPot activity, and then switching the output format to Findit (a). First, add the JCL file using the "Best" output format. As you have noticed, "Best" is the only available output format when you add a new HotPot, because at that point the server doesn't know what kind of file you are going to add. Then, once you have added the HotPot, go to the "Edit settings" page, and now you will see all the output formats that are available for JCL files, including the "Findit (a) from HP6 JCloze xml" that I mentioned earlier.
good luck!
Gordon