Hi Henri...Russell Motors still have the correct rivets I believe...
When you have a set check that the shanks are all the same length and machine them to the shortest if they are not...
The rivets are reasonably tough and riveting them by hand is a pretty horrible job as it is difficult to get the rivet to form and 'swell' properly..
It's a guess but I'd put money on it they were machine riveted at the factory...The rivets can be tapped through the flywheel and main shaft flange prior to riveting...
I made a jig to hold the flywheel which had adjustable screws with hardened pads in them to screw up tight against the back of the rivet heads...Note that the rivet head thickness varies so some form of adjustment is required or the heads need to be machined to make them consistent...(if the ones you get are not)...
Some racers replace the rivets with high tensile screws and that mod works well I'm told but I haven't tried it myself...Ian
email (option): ian@wright52.plus.com