If you have access to a lathe, machine new rivits, then apply heat and rivet them in place.
Start by grinding the heads of the old ones, drive them out, and machine the new rivets and install.
I leave a couple of the old ones in, then also replace them after the others have been done.
It helps to machine a mild steel mandrell (a bit smaller than the hub ID) to pass through the hub, and belt the rivets against. It needs to be held very tight in a vive ( and support of the other end is recommended).
Oh how we miss the passing of the blacksmiths!