Thanks for all the great ideas. Does anyone know if those J-Tek shifters would work with a friction setup or only indexed? They look really clean, but boy are they expensive. It's $200 just to buy two of the shifters and brake levers. The solution shown above using the cross type levers that go around the bars should work with a set of bar end friction shifters, but obviously wouldn't be as slick a set up.
I've thought of switching to indexed shifting, but I think it's just too much of a pain and too expensive to be worth it. By the time I relace the rear wheel with a cassette hub, buy new derailleurs and shifters, plus a new chain, I will have spent nearly as much as I did to build up a complete vintage Colnago Super with Campy SR parts!