It is a nice piece the way it sits,I suggest rearranging 1st before chopping.
But like someone said above you could place the slower growing SPS at the top of that Pukani.
You mentioned that you have roughly 8" from the top of that Pukani to the water surface line that is good distance for growth.
If you still planning on chopping maybe try this.
Chop the bottom half flip it and place it on another side of the tank and you have a large Pukani a smaller piece and the branching Tonga.
