Best of luck with that task. I've not seen them listed by Minor suppliers.
The original items, 33 & 34 on the illustration, are listed as BRP 1206 and BRP 1108 respectively. Quantities being listed as 7 and A/R.
Sometimes searching these original numbers, will produce modern results, but not in this case.
If you measure the hole size, you should be able to find something.
For example, this listing for Copper Rivets on ebay for use on classic Jaguar & Daimler.
https://www.ebay.co.uk/itm/284281839610
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