At 5'10" to 5'11" tall, 198 pounds is not going to look muscularly crazy on stage. However, if you want to get on stage any time soon, that is probably the class that I would look at.
I am not going to be the one to work with if you need to hit a weigh in. I'm all about putting on the beef, but I never worried about a weight class. We were just trying to get as big as humanly possible.
I will say, if you're not willing to "force feed" then you probably won't make it. If you're the type with the fast metabolism, you are going to need to eat like a bear preparing for hibernation to pack on that kind of muscle.
What does your diet look like now?
Also, I would not fuck with T3 in order to boost your hunger. That T3 will be revving up your metabolism even higher. I would think that THC would be a much better tool in the quest to be hungry than T3 would in this perspective.