Originally Posted by VintageSteelEU

You mean the thing below? I'd need to clean it a bit (sorry, it came off a FD I got for parts and in a sorry state, so didn't bother making it presentable yet, hence a bit of caked mud on it), but if you're willing to wait for a delivery from the UK, happy to clean it up and send over. It's steel. I might even have some domed nuts the right size if that was your preferrence.
Alternatively, brake cable fixing bolt for generic single pivot side pulls looks basically the same and has the right length. I got some new (don't remember who makes them at the moment) and they even have domed nut. Though the ones I have diameter 0.2mm smaller (5.6) than the Huret bolt I have (5.8), but they are probably made in several sizes.