It's been almost two weeks since I actually was in the shop, but I finally have time to update the project status. I reshaped the heel of the neck, removing more wood from both sides along the curve. Using a small chisel, then various grades of sandpaper, I took off about 1 mm in various places. I think it's a quite nice shape now.
I plan to create a personalisation mark on the button, but am unsure of the best method. My carving skills are probably not up to the level I need for what I have in mind, but I don't have the resources to create a stamp either. I had best practice on scrap first!