The local swap meet I went to after our Chicago C&V ride yielded a Sakae 'Custom' drop bar, which will do nicely I think, esp for $10. It's wider so will likely be more comfortable than the 'Randnner.' The bars I have were certainly original to the bike, just as spec'd in the '83 Miyata catalog--mine still have crusty original foam covers on them. The 'custom' bars with new/old aero levers and red bar tape: more comfy, safer, and more stylish all at once.
With all respect to Mr Zinn I'm not that worried about catastrophic metal failure on these ala the DeHavilland Comet. All that happened with mine is that they got a bit loose, which was annoying but (at my pace) not really dangerous. The only 'technical descent' I am concerned with is falling off the darn bike, which I try not to do.