The past couple of weeks I've been gradually getting the neck down to the final shape and dimensions. I started by using small chisels and scrapers, but that was quite slow. I ended up doing the rough shaping with a sanding drum mounted on a drill press. This took off the bulk of the extra wood. I then got it down to the final profile with a sanding stick and machinist's files.
After getting the neck to the final dimensions I removed a bit more material from the heel of the pegbox with small chisels and machinist's files.
Once I had the profile right, I noticed that the base of the neck wasn't symmetrical. The left side had a different angle than the right. I used an adjustable machinist's protractor to mark the correct line, then used a belt sander to achieve the proper profile. In the proces I caused a bit of damage to that side of the neck, so once I cleaned that up the neck ended up a bit narrower than optimal. I'm hoping it doesn't cause any other problems.