For upset training I think you should have side by side seating as that is the likely configuration of the aircraft that a student will have when the bad thing happens. My question would be how aerobatic do you want your trainer. If you are just doing upset training than a Beechcraft Sport or Sundowner with the aerobatic kit would be fine. If you also want to do proper aerobatic training then the lycoming powered Zlin would be a good choice and they are certified by the FAA. A Slingsby would be another possibility. All are tricycle gear
Personally I would hook up with a good fairly large school. They can handle all the management of the aircraft and come with a built in student supply