You win: It's a Regina Extra 12/18. So, now that we have that settled, I assume that all those Shimanos you've posted no longer apply?

And going slightly off-topic, what can I do to give the brakes better feel? I've cleaned and lubed the calipers and added Kool Stop salmons, but they're not terribly confidence-inspiring. Perhaps new cables would help? The levers are pre-91 Athenas, I believe.