The most important thing to figure out is the speed and direction of the PTO - some Cat 0 PTOs run counter clockwise, some run at high speeds. Either will present a challenge for you. If I had to guess, yours will run clockwise (good) and fast - like 2000 rpm (bad).
That will limit the availability of tillers that will work. It is relatively easy, though not cheap, to find a 540 RPM tiller. Keep in mind you could always convert a Cat 1 tiller (48 inch wide or less) to Cat 0 - the main issue there is making sure you have enough lift power to get the thing off the ground.