I size my swivels a little differently, because I am not worried about fast rotation, or a lot of flash. I fish the CA Delta, which has lots of tulles and weeds, and the bass are always eating bluegills and crawdads. So I want a lot of thump, so the bass can find my baits, so I fish bigger blades.
I use larger Indiana blades, and pull them through tulles, so I size my swivels by how strong a split ring I can fit through their end holes. I don't try to make them so big that both the split ring wires go through the holes. Instead, I pick a strong split ring, and then make sure the wire will pass through once. It doesn't take too strong a split ring. I generally use one I've taken off a crank bait when I've upgraded the split rings for the hooks. Then I space the split ring so that the "cross over" part, the space between the two wire ends where it's still a single wire, is in the swivel hole when I put it on the swivel. That way I don't rip the bigger blades off in the tulles, or cast them off on s long cast, and it still allows the blade to move freely.
I seldom fish my blades in open water, since the fish in the Delta live either in the grass, at the grass edges, or up in the tulles when the tides up, and they're hunting.