That is a characteristic (and a preferred one) of most flat bottom trainers. When the student gets in trouble he adds power and lets go of the sticks. The airplane levels itself and it begins to climb. The Kadet was designed that way.
I have flown a Senior Kadet with the .65 Sportster and it was a perfect match. Large prop, (14x5) turning 8,600 RPM and idling at 1,700 RPM. Just because the left stick goes all the way up, doesn't mean you have to push it that far. I could take off at 1/4 throttle and it looked like the airplane was flying in slow motion. It would do BIG SLOW LOOPS all day long at 1/2 throttle. With that big prop idling so low I could stop it dead in the air with a little headwind.
The Senior Kadet is a big, lightweight trainer. The .65 with a big low pitched prop would pull it through most windy conditions with very little effort. The heavier engine weight also helped its flight characteristics in the wind. My kadet had some downthrust but nothing extreme.
Your TT .46 (if its like any of the the 5 I have) is putting out pretty decent RPM's at full throttle and is trying to pull the airplane at a much faster speed. Thats why you are getting all the lift.
The Sportster .65 is all low end torque with a big prop, power not speed. Thats why I said you need to prop it like a 4-Stroke. If you try to treat the Sportster series of engines like current production ABC smokers, you will be disappointed. Its a puckety-puck kinda engine that really shines on big lazy, slow flying airplanes, and will last a lifetime.