Update time! I followed a lot of the advice from this thread and it worked out great, so thanks. Short story: I stuck with 27" wheels, and used a Tiagra 4600 rear hub (130mm) with a Shimano 8 speed cassette (HG51). I left the rest of the drivetrain alone. I also built a front wheel with a Shimano dynamo hub (3N72) to power a Busch and Muller Eyc Senso front light and a B&M Toplight Line Plus rear.

Longer story:

These were my first two wheel builds; they turned out great and were a lot of fun. I just followed the instructions from Roger Musson's book. Here's the front on my homemade stand:



I love the dynamo lights. No worrying about batteries, charging, or even turning them on or off; just swing a leg over and go.

The rear wheel and 8 speed cassette work fine with the stock friction shifters and derailleur. I probably need to tweak the chain length, but I'll wait for the next new chain for that. I haven't tried cold-setting the rear dropout width from 126mm to 130. The new wheel fits with a little bit of fiddling, although I may regret it if I have to deal with a cold, dark, roadside flat repair.

I still wish there was better tire availability for 27" wheels though. When I was ready to buy I couldn't find Gatorskins in stock, so I went with the Schwalbe Marathons. Now the Gatorskins are available.

Now I just need a new wheelbuilding project. I'm thinking about building a 650b wheelset for my Marinoni...