I was looking at Nashbar Jail Brake Road Calipers for a conversion like you're talking about
:
http://www.nashbar.com/profile.cfm?c...eid=&pagename=
Just make sure they have enough reach. I THINK those will but I'd try to find someone who is using them to be sure.
Then I got cheap and stayed with the Dia Compes. If you put some Kool Stop Continental pads on your current brakes you'll probably be really happy with them. I think it about doubled the stopping power on my bike.