Several days of finger plane work and lots of scraping later, and I’m provisionally satisfied with the shape of the belly plate. The profile is slightly low in the middle, but that’s the limitation of the material I started with. The scraping also revealed the crack that was noted on the original slab. If the spots become an issue, I’ll try infusing them with a bit of CA glue before final finishing.
Next up is going through the same shaping process on the back plate. It’s physically harder work because of the hardness of the wood, but I’m not in a hurry and will take my time.