IMO, Regina freewheels of that era had the sloppiest of all machining and tolerance. The only thing that was superior was the durability of the sprockets and their finish in either gold Oro or nickel. I'd not loose any sleep over the destruction of your rusty Regina in order to rescue the hub.

Thank you for the better pictures. I don't see the same thing in the three new pictures. Your Regina appears to have lived a neglected life. Time to recycle it's remains.