Chim-I used another approach for the hooks - chain slots. These worked well on the B7500 for the 10 years I had it, so it was one of the first things done when the L3200 arrived. Heavy angle with slots that will accept 3/8" chain are bolted to the bucket. Chains can drop in and take loads from the front or rear. Extra chain can be dropped into the remaining slots so there's no long loose end dragging.
If I want to use a nylon sling, I just hang it on a short piece of chain and drop both ends of the chain in slots so it hangs in a "U". In the pics below you can see the pieces of angle and how I fasten the brush forks with some chain and a hefty load binder with a short piece of strap.
Just found your post and photos. Really like your design, especially how they can be used from front or back and the short chain for straps.
What size angle iron did you use?
I have a 30 hp and a 37 hp tractor that I need hooks for.
Do you think that this open angle design is strong enough or would gussets be necessary? One of the buckets does not have the forward bucket edge resting against the front of the angle iron.