Keep your 205 vacuum advance distributor! If your vacuum chamber gets a leak, you'll have to order a new chamber. As Jeff Hibbard points out, the 009 does not work well for around town driving. The fact that most VW parts places only carry the 009 shows how little most suppliers understand. Mechanical advance is a full race item (unless you don't care if your car runs crappy). This is my current thinking. I'll post more here soon.
I found that a $17 Wells RV1001 vacuum chamber purchased at AutoZone is just the item. This probably doesn't work with all 205 distributors, so I'll put my exact distributor number up here sometime. It took me weeks to find this supplier. Prior to finding this item, I had heard stories of vacuum cans between $40 and $300.
That is my happy 205 distributor with the yellow tubing between the vacuum chamber and the carb. The car runs much better with this than with a 009. Note that this is vacuum advance, so it goes to the venturi vacuum on the carburetor. The dotted line is around the closed off manifold vacuum.
This is the old Solex carb. I've got some new photos with the Weber. Same distributor and still works great.
Tools: socket wrench (if you take the distributor out), small screwdriver, maybe circlip pliers, timing light?
Parts: vacuum or small fuel line tubing.
I have added a CompuFire point replacement. Nice. It only took about 30 minutes all told. My tachometer has some funny behavior, but I'm still investigating that.
Tools: crimping tool , ignition wrenches for the nuts on the coil.
Parts: crimp-on terminals.