I would go with either a BushHog, Rhino, or Woods front end loader if you wanted an aftermarket loader. Of course you could still get a Kubota loader for that model I assume. The reason I say those three aftermarket brands is due to parts availability and dealer support throughout the nation. I would also recommend a mid-mount loader instead of a front mount loader.
For the 4-in-1 bucket I recommend W-R-Long or Bradco (make sure when you order the loader to get a skid steer type attachment option).