The picture below shows 3 versions of "Racers" with identical measurements.
The brake to the right - to my knowledge one of the last versions - is what I thought at first glance to be the same as the ones shown by oldlugs (which I think are "Racers" as well). Except from the black washers/bushings instead of the common red ones and the bigger brakeshoe mounts.
Both details I have not seen on "Racers" so far.