I've seen other 50's-early 60's bikes with them but don't recall makes other than another Schwinn. When I got the Paramount it had a Nitto stem and generic bars, some research indicated the MK bar and Titan stem were OE. Over the good part of a year of searching I found first the stem and then the bars, and finally a set of Weinmann Vainqueuer 999 early gen brakes/levers to complete the set. Luck and circumstance played in my favor on this one - for a change.

As an unexpected bonus I stumbled across a dual-bottle Coloral wire handlebar cage in great condition at the co-op for $10 (!!) early this year. Not quite period correct but I don't care - it looks great..