The tab washer is standard on various bits made by Brits. Most common on your SU throttle shafts. Most supply houses that sell carb rebuild kits should have the tab washers as well.
The funny looking lock nut is indeed a lock nut. The old style before nylocks were invented, the top of the nut is deformed to interfere with the threads on the bolt or stud it is mounted on. Good ole USA engineers did much the same thing by taking a perfectly normal nut and tapering one end then deforming it with a punch. Deformed lock nuts are still available at many auto parts stores.

Mike!