I'd say leave it as is; except for the wheel. If anyone else (or you) ever wants to convert it back, you'll miss those braze-ons. That, and the paint job looks pretty nice from the picture. But it's up to you.

A spot of encouragement: I was actually lucky enough to get a 700c wheelset to work with calipers designed for 27" wheels - so it is possible. That said, you should find a friend with a 700c wheel to see if yours work. You may get lucky. Otherwise, its a new caliper or a drop bolt:

http://www.sheldonbrown.com/home-drop.html