Those do indeed appear to be Universal Mod.51 "Extra" calipers, introduced in 1951 and quite appropriate for a 1958 model bike.
Super 68s (ca. 1968) used the same quick release arrangement, but had thicker, more rounded caliper arms. By necessity, the length of the quick release mech was proportional to the length of the caliper arms.
The Universal Brakes page on Classic Rendezvous site is not complete, as it is missing a picture of the Extra calipers. The "Dural" calipers shown are one step down from "Extras".
I'm image there are of photos in the Pic of the Day album showing the Universal calipers with quick release levers during the 1950s. Here's Coppi's Tour de France bike from 1952:
http://www.wooljersey.com/
Aldo Ross Middletown, Ohio, USA
----- Original Message Follows -----
From: j.kleijn <jeroen.kleijn@ziggo.nl>
To: <classicrendezvous@bikelist.org>
Subject: [CR] Universal brake set
Date: Tue, 28 Apr 2009 09:47:05 +0200
> Hello,
>
> I want to buy a brakeset on ebay
>
> The seller claims it is a late '50 Universal mod 55 (??)
>
> I need such brakes for the restoration of a '58 Locomotief
> racebike
>
> small foto's I have put on
>
http://cid-a401f95c1cb8b737.skydrive.live.com/
>
> can anybody comment on this?
>
> Thanks
> Jeroen Kleijn
> The Netherlands