The 3-point hitch assembly is unique to that machine within the Kubota line.
No other set of parts from a 'similar' machine will fit properly---they might be force-fitted and they might move around, but they won't be correct and if placed in a bind by hydraulics might break something like a housing. If you do this watch everything move slowly and carefully under different loaded configurations (different implements) and be prepared to make modifications. In the end, this won't be a satisfactory solution.
Get a parts book and start making a list of part numbers for your dealer to quote. If you leave off the bolts, pins, chains, and assorted locally-sourced (sourceable) pieces the dealer might get you the steel parts for $1,500.
A complete (or even partially complete) set of L-35 used 3-point parts did not exist in the US about three years ago when I did the same thing. By al means look as something may have changed. Send me a Private Msg if you turn up two sets or don't want to buy the set you find.
One consideration is that if you do obtain the parts the machine resale will be increased tremendously and you may get your money back someday.
Another consideration is to think about just how often the 3-point parts will actually be used. Time will inform that removing the backhoe is a royal PiA. And if it's been sitting, you may find the first removal extremely difficult. Another thread on this Forum reported one of the mounting ears was broken during removal of a reluctant backhoe.
My observation is that no matter how the machine is configured, the 'other' setup is needed to do a job. After wrestling for an hour or two switching over, time to complete the job is gone.
Remember, when the hoe is removed, you've still got to reassemble the 3-point gear---it can't ride along with the hoe when mounted.
We finally left the L-35 set up as a dedicated backhoe and it's become the go-to machine. The second unit rigged for 3-point is used less frequently. Perhaps you should consider two machines as we have.
Regarding the bucket: you need to find a competent heavy equipment (I'd think heavy construction equipment or oilfield, not structural iron-hanger or residential steel stud) welder to rebuild the bucket. When you do so have him apply cross-hatched hard wear bands to extend its life. Good welding and required materials will not be cheap. Compare to ordering a new bucket (you might, just might find a used one at a tractor salvage yard, but I doubt it) and you might determine there is no savings in rebuild.
Getting that old bucket off is going to be a bear. Use a large diameter brass punch or drift and a much bigger hammer. Heat carefully applied may be required.
The L-35 is a great little machine; we wouldn't trade ours unless we upgraded to later model or size in Kubota's line.
Please post back your continuing experiences so we may all learn.