That does look vert slick. Not many available though, and it looks like the only one on Etsy now is $135. Either a former owner or vandal wonkeyed up my gas cap on the '86 R 65 I bought last fall, so the key doesn't fit. But I can get it on and off no problem, but it looks like it's been jimmied with a screwdriver.
Which begs the question - with exposed fuel lines and petcocks just below the fuel tank, why in the world have a locking gas cap? :-?