nial - this would work if the pin threads are of sufficiently smaller diameter. Obviously, you have to be able to get the sleeve onto the pin. This, is, however, just a better shim; a shim put onto the pin. Now, if you refit the hook to a slightly oversize pin sleeve, you have a new, properly fitted joint. The only issue with sleeves is to refit to the non-shimmed side. Welding puts down a "permanent shim" that is then refitted. Remachining a welded-up pin should be no problem as reaming/miling/fiing should be no problem for a welded-up hook. A glued-in shim can be a as hard or soft as you wish and can be fitted as above. The above pin shim could also be a sheet shim glued onto the pin.
Many ways to skin that cat!! The issue is figure out what is amiss within the joint and what will make the most efficient combination of economical, aesthetic, mechanically sound, and durable repair to the joint. Differing craftsmen may get to the same final point using differing methods.
