I reviewed your data plate manually. There is good news and not so good news.

1) Your car is indeed an original 400 Sport model. The "3JF" means you have 2 separate options in Group 3, "J" which we are not sure what it means and "F" which was the 400 model.

2) The not so good news (depending on your desires) is that your car left the factory with a TH 400 transmission under it and only 2 pedals on the floor. Someplace in its life it got converted to a stick car. I only saw the one RH factory traction bar under the car in the photos - if the left side one is missing and there is no Riv Nut on the rear frame rail and reinforcement plate on that side under the rear seat, that would pretty much confirm that.