Originally Posted by
thunderworks
If you want period correct, check ebay for Weinmann 610 center pull brakes. If you don't care about period correctness, your LBS should be able to order a "standard reach" brake that does not use a "recessed" bolt on the back. I'm pretty sure Shimano makes a current, inexpensive model of some kind that is the right reach and has a conventional pivot bolt.
Just a caveat on this...
AFAIK, if it's a standard Mirage (and not a Super Mirage), it came stock with 27" wheels. If OP has 700c wheels on there now, the standard Weinmanns might not reach. I ran into that problem converting mine to 700c - you can't quite get the pads down far enough to make it work with that brakeset.