Before you go to the time and expense of having your drum turned, you might want to set up your table first and check it for square to the drum. Depending on your pattern thickness, you will only be using the bottom 2 inches of that 6” drum, and it may not need to be turned at all.
I would also recommend using more aggressive sanding belts like 40 grit or even 36 grit. Besides making the shaping of extremely dense hardwoods much easier without burning, it gives the glue joint more tooth. I use 36 grit on my footed risers. .02 cents worth.
Kirk