I'm not selling it, and the charitable view is to say that whoever is, doesn't know much about Enfields. First up, it may be titled as a '58, but that style of frame was made for '54-55 only. Enfields did not supply KMh speedos back then, either.
The motor is a Yamaha - 'nuff said. Why the vendor hasn't put that little piece of information in the listing, one can only wonder.