Thank you. If you could measure up and stick the info here, it's available for anyone else who needs it. I have a lathe, but not that proficient, but have access to a bloke who does some wizard stuff......
Beetle/VW ones are readily available in stainless but I can only find 8mm and 9mm sizes.
Done a fair bit of research and initial plan is to a) replace all the mounting bolts, b) pop the pins out, c) give them a smack with a ball pein hammer, d) swap top and bottom pins over.