A good way to find out this info is to go to Kubota.com and look at the attachment reommendations from the company, not that their site is all that friendly about mower recommendations.
If you have the 80 PTO HP model you should be able to easily carry a 10 foot rotary mower or larger, but you're talking some big bucks. The 3pt hitch is listed as a category II, everything is going to cost more than a compact tractor. They consider the M9000 a utility tractor.
As for most implements you buy for that model, you're going to want attachments that are a little wider than the rear so that you can get up along fence lines, and building etc.
John