I will mention to you that buying a new one will result in a nice looking cap,..... That may not "cinch down" as tight as you would want. The repo cam ramps are not spot on. I made a tool to bend them, and it worked to make the new cap fit and seal as it should. Chunk of bar stock with a slot hack sawed in it. That metal is quite thick, and placing the cap in a vise to hold it while bending thick metal made me nervous, but if was a non-issue.
Down to 1 BSA, 2 Triumphs, 1 '56 Chevy
1 '65 XLCH, Hernia Gift, on the way to Japan!