I finally got around to the distributor modification. Pulling the drums off the shaft was a real challenge. After trying various things my solution was to find a series of 1/2 inch sockets that had an opening large enough for the shaft to slide through, but with a socket size that matched the diameter of the inner portion of the drum on each shaft. I then inserted this set up into a vice to push the drums off the shafts from the bottom such that they slide out the top of the shafts. This was important, since my original attempts were trying to push the drum off from the top down, which was physically impossible given their design (which was difficult to assess visually until I eventually succeeded). Even using this set up, it took considerable force from the vice before the drums let loose of the shafts - on the 16v I actually had to tap the handle of the vice with a 10lb sledge hammer before it let loose:
