Hi, I had a bag blanking grommets back in the 80's ago from work that were almost exactly correct, with just a slight radius difference, I no longer have any I am afraid, but there will be bags of the things out there for pennies each if you mooch around online ......this sort of thing;
https://www.vintagecarparts.co.uk/pr...rommet-no-hole
The link is just to show you what I mean, I don't have any later BSA's so cannot measure the grip drilling size to enable the start of your search.
ATB, Ed