Charles,
I agree totally with George Watkins in respect to make a nice clock out of the burl. One of the realities about these type of nice "slices" is that, as soon as it get cut into pen blanks or any other smaller blanks, the wood looses it beauty and its natural formation of grain, colours, etc, never the same thing again...!
The Cocobolo board I would cut it into triangles and make a segmented platter or a bowls depending of how many layers and final size you want...!
Just some thoughts...!
Good luck
Cheers
George