Did exactly the same thing on my F1 during the rebuild

my carbs were found to be so gummed up with what looked and felt like sandstone that the decision to replace them was easy, I would go the e-bay route. However, for interest, and in case you don't find any for a while I did post on the US site and apparently some have had some success using an epoxy like JB Weld. Its not a stressed part really ( till you try and remove the pin

) so its only a matter of whether fuel will affect it, apparently its OK. Could be worth a try if you are stuck. Would keep an eye on it though