Has anyone ever actually SEEN one of these?

Thinking along those lines, the small cube Gen1 Hemi's weren't powerhouses although they weren't performance engines. Low compression, mild cam 2 barrels.
This is true but keep in mind cube for cube vs the competition these early HEMI engine mopped they floor with them.

After I retire, I’d d like to find one of any size and use it in a chopped, channeled & stretched 33 Dodge or Plymouth hot rod.

Nothing looks more right than a HEMI in a Hot Rod.
It doesn’t even have to breath fire. It just has to be a HEMI!