A friend requested a special stand to display her fathers bonsai trees. I have seen this spiral design before and decided to give it a try. The most difficult part of the project was finding a BIG block of Koa.
That IS a big block (my biggest chunk is about 10×10x15). Was the shaping done by saws which left you some scraps or was it all done by carving and grinding?
Your block should be big enough. Mine is nearly an end table.
Because of the spiral, I couldn't use a saw. I tried, but had little success. I do have a power carver, but even that got tight fast. My Fein Multimaster worked well in coarse shaping. The gouges worked well, with a few scarey moments where I almost split it by being impatient.
Give yourself a couple of days and go for it. Send pictures when you're done.