[flatheadmurre]

If the splines are worn it´s real tough to get anything to last...the pins get sheared right off and falls out...that´s why the "safety" pins with a springclamp to keep parts from ending up between gears was invented.
If the spline is nice and tight it will work fine with a bolt or rivet...
And the original rivets was solid ?? that looks like a hollow rivet that should be installed like a brakeshoe rivet....