I agree that it is possible to convert these implements to true CAT 0 style but why would you bother? As I understand it, there is a ready market out there for these, just the way they are and frankly, not one of them impress me all that much anyway.
If you have a Case GT with a 3 pt hitch, then a set of Brinly double disc harrows is far more useful than that toy from Sears. The same holds true with the turning plow. I don't see any adjustments on that one, like you do on a Brinly.
I'd sell off all of that iron for as much as it would bring and then keep my eye open for items that were for 3 pt operation when they left the factory.