Kip, with my little experience with mulberry, I would leave first ring of sapwood!
Mulberry seems to be of large ring. Fast growing?
The sapwood I had to drawknife was the toughest, ever! Period!
Now from my experience, you could dive right in with this pristine stave. Or you could forego, and find another piece of wood, species, like osage. and have at it!
Then after a few bows, pick up this stave with a different look and feel, and build something special!
It is a nice looking, clean stave!
Hindsight is...... ya know!
Just look at that last pic, looks alot like Yew!