Colleen, welcome to Canreef! I believe that if you are going to use an Ushio 10k bulb, the pulse start is the correct ballast. This is because Ushio (and other Europen bulbs) don't have a built in starter.
Steve (Stircrazy) is probably the best resource here as he just researched adding 250w bulbs to his tank not too long ago. He'll post about 4 in the morning or so
What do you have or plan to have in the tank? Also, try and get around to some of the tanks in Victoria to get a first hand look at the different bulbs and how they look in person.