Memory Alpha has this: https://memory-alpha.fandom.com/wiki/Mount_Rushmore_National_Memorial But it's interesting that the storyboard has the fifth head on the opposite end and the ear looks pointed. Granted, it's probably just the angle / perspective, but it would have been a cool way to honor the Vulcans and First Contact:
The script clearly states it's supposed to be an African American woman. And the deleted scene on the DVD and Blu-ray shows it is clearly not a Vulcan
I believe that is (at least part of) their point. This added head is different to the one they ended up going with. It looks different and is on the opposite end of the line-up.
It looks similar. The "point" off to the right is part of the mountain, not an ear. Also, if it were a Vulcan they'd have indicated the eyebrows on the sketch.
A Vulcan on Mount Rushmore seems rather unlikely, as all of the other four heads are U.S. Presidents.