Hi all, thanks everyone for their help.

I think I'm going to pick up a set of those Tektro 800A's. They're a really good price and look fairly nice, not out of place on a vintage bike at all.

My experience with dual pivots has been generally very good. On my other bike (that was designed to take 700c wheels) I switched out a pair of old single-pivot shimano 105 side-pulls for a pair of tektros and the difference is night and day. I have heard the complaint about DP's being "spongy" feeling, although I must say I rather like it, it feels more graceful almost when feathering the brakes. I will consider upgrading to koolstops on the new sidepulls in the future though, incase I feel I still need extra stopping power.