See your owner's manual for Kubota recommendations as to size and weight of specific implements.
All depends on your horsepower and traction (machine weight, tires, 2- or 4-wd, ballast, gearing). Heavier the implement the better performance you'll get.
Be sure you buy a brand for which you can obtain replacment tines---sooner or later you'll notice one missing.
Note how the tines are adjusted and restrained. How about the backside having a dirt-flap or trap-door to smooth out 'furrows' as you pull forward.
Can you weld chain hooks on each corner to pull a drag as part of your final pass when working soil? Is there sufficient material to weld a bracket to take a trailer ball or receiver hitch ball mount (pretty handy to snuggle up beneath a trailer tongue to lift and move it or light tugging with a chain)?
Is the frame beefy enough and have enough room you can add ballast if needed? A chunk of broken sidewalk will work wonders for your soil engagement capabilities.
Good luck as you go forward. Please post your results and pictures so we may all learn.