According to Red Sutherlands, the 9.5mm is pretty much the standard now, and you can drill the arms with a 3/8" drill to convert smaller size co tters to 9.5.
When you buy a pair, there is generally no need to file them. Unless the shop sells you a pair from different lots.
Having the crank off just a couple of degrees from 180 takes me right ba ck to an early 70s Gitane Interclub.
Steven Johnson, Kandahar, Afghanistan