Can the Eternal Mangekyō Sharingan be obtained by implanting a normal Sharingan?
Here's a simpler thought:  you can't obtain something greater if you have something lesser to offer.

We know that obtaining the Mangekyo Sharingan requires someone to witness someone close to them being killed or lost.  Some of the more prolific wielders obtained this by killing someone close to them, with the notable exceptions of Madara and Itachi who only witnessed someone close to them die.

One of the changes when someone with the Eternal Mangekyo Sharingan undergoes is that the tomoe of the previous MS wielder is blended in with their own as a secondary pattern, similar to how a kaliedoscope blends in multiple pictures.  This is evident with the final look of Sasuke's own EMS.



With that, it makes sense that a prior Sharingan would have needed to have been an Mangekyo, since there wouldn't have been a new tomoe pattern to include into the kalideoscope.